The UK Independence Party (Ukip) was blaming an "internal error" today for keeping its party's name off ballot papers in London, potentially losing them the chance of representation on the capital's assembly.

After nomination papers were filled in incorrectly, the party's contender for mayor, Lawrence Webb, and candidates for the London Assembly were listed as "Fresh Choice for London", rather than Ukip.

Party leader Nigel Farage said the bizarre blunder probably meant large numbers of would-be supporters assumed Ukip was not taking part in the ballot and gave their vote to someone else.

The eurosceptic party had been polling at around 8% in the capital in the run-up to yesterday's vote - enough to secure third place in the mayoral race for Mr Webb and possibly two seats in the Assembly, where Ukip has been unrepresented since two members defected in 2005.

"We can only put our hands up and say sorry to voters who wanted to back us but couldn't find our name on the ballot paper," said Mr Farage.

"We hoped and expected to get two seats, but this has cost us dear. It is a lesson hard learned."

The mistake may have boosted Boris Johnson's showing in the first round of the mayoral poll but is unlikely to affect the final outcome, as most Ukip voters are thought likely to give their second-preference votes to the Conservative candidate.

Elsewhere in the country, Ukip performed well despite seeing only limited gains in council elections.

With counting complete in 177 out of 181 councils, the party had won nine seats - unchanged from their position at the start of voting.

But Mr Farage said they had seen their share of the vote rise across the country, but had been unable to translate this into seats on councils.

"Our share of the vote is going up and up and up, very steadily, very surely," he said.

"Yes, we are getting Conservatives voting for us but it is not just Conservatives because those results are the same in Labour seats as they are in Tory seats.

"We haven't quite got to the level where we are bursting through and winning seats in very large numbers. If we continue this momentum, then next year and the year after we will start to win council seats in real numbers."

He said that Ukip's appeal was not simply confined to European issues.

"We are talking about immigration, the fact that we still have a total open door to the whole of eastern Europe. We are talking about green taxes and the damage it is doing to British industry. We are talking about the need for selective education. There is a whole raft of policies here," he said.

"For the Tories to attempt to eat into our vote, it will mean Mr Cameron changing its entire manifesto."

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  • London Mayoral Election

    Prime Minister David Cameron and his wife Samantha leave the polling station at Methodist Central Hall, Westminster, London, after voting in the mayoral and council elections.

  • Local council elections

    SNP Deputy Leader Nicola Sturgeon casts her vote at Broomhouse Halls polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • Local council elections

    Scottish Labour leader Johann Lamont at Berryknowe Resource Centre polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • Local council elections

    SNP Deputy Leader Nicola Sturgeon arrives to cast her vote at Broomhouse Halls polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • Local council elections

    A voter arrives at Berryknowe Resource Centre polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • Local council elections

    Scottish Labour leader Johann Lamont (left) and local candidate Alistair Watson (right) at Berryknowe Resource Centre polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • London Mayoral Election

    Prime Minister David Cameron and his wife Samantha leave the polling station at Methodist Central Hall, Westminster, London, after voting in the mayoral and council elections.

  • London Mayoral Election

    Ken Livingstone and his wife Emma arrive at their local polling station in north London with their son Tom, to cast their votes in the mayoral and council elections.

  • London Mayoral Election

    Prime Minister David Cameron and his wife Samantha arrive at the polling station in Methodist Central Hall, Westminster, London, before voting in the mayoral and council elections.

  • London Mayoral Election

    Ken Livingstone and his wife Emma leave their local polling station in north London with their dog Coco and children Mia and Tom after voting in the mayoral and council elections.

  • London Mayoral Election

    Prime Minister David Cameron and his wife Samantha leave the polling station at Methodist Central Hall, Westminster, London, after voting in the mayoral and council elections.

  • London Mayoral Election

    Ken Livingstone and his wife Emma leave their local polling station in north London with their dog Coco after voting in the mayoral and council elections.

  • London Mayoral Election

    Ken Livingstone and his wife Emma leave their local polling station in north London after voting in mayoral and council elections.

  • London Mayoral Election

    Prime Minister David Cameron and his wife Samantha leave the polling station at Methodist Central Hall, Westminster, London, after voting in the mayoral and council elections.

  • London Mayoral Election

    Ken Livingstone and his wife Emma leave their local polling station in north London after voting in mayoral and council elections.

  • London Mayoral Election

    Ken Livingstone and his wife Emma leave their local polling station in north London after voting in the mayoral and council elections.

  • London Mayoral Election

    Labour leader Ed Miliband and his wife Justine arrive at their local polling station in north London to vote in the mayoral and council elections.

  • London Mayoral Election

    Labour leader Ed Miliband and his wife Justine leave their local polling station in north London after voting in the mayoral and council elections.

  • London Mayoral Election

    Labour leader Ed Miliband and wife Justine arrive at their local polling station in Highgate, north London, to vote in the elections for the Mayor of London and the London Assembly.

  • London Mayoral Election

    Labour leader Ed Miliband and wife Justine arrive at their local polling station in Highgate, north London, to vote in the elections for the Mayor of London and the London Assembly.

  • Local council elections

    Ballot boxes are sent out to polling stations around Edinburgh from the council headquarters ahead of the local elections tomorrow.

  • Local council elections

    A voter arrives to cast a vote at Broomhouse Halls polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • Local council elections

    A voter arrives to cast a vote at Broomhouse Halls polling station in Glasgow, as Scots go to the polls today to elect their local councillors.

  • Local council elections

    Ballot boxes are sent out to polling stations around Edinburgh from the council headquarters ahead of the local elections tomorrow.

  • Local council elections

    Ballot boxes are sent out to polling stations around Edinburgh from the council headquarters ahead of the local elections tomorrow.

  • London Mayoral Election

    Boris Johnson and his wife Marina Wheeler leave their local polling station in London after voting in the mayoral and council elections.

  • London Mayoral Election

    Boris Johnson and his wife Marina Wheeler arrive at their local polling station in London to vote in the mayoral and council elections.

  • London Mayoral Election

    Boris Johnson and his wife Marina Wheeler leave their local polling station in London after voting in the mayoral and council elections.

  • London Mayoral Election

    Deputy Prime Minister and Liberal Democrat Party leader Nick Clegg arrives to cast his vote in the local elections at the Park Hill community centre in his constituency in Stannington in Sheffield.

  • London Mayoral Election

    Deputy Prime Minister and Liberal Democrat Party leader Nick Clegg arrives to cast his vote in the local elections at the Park Hill community centre in his constituency in Stannington in Sheffield.

  • A man watches the vote count status on s

    A man watches the vote count status on screens inside City Hall in London as results are tallied in the London Mayoral and local elections on May 4, 2012. Prime Minister David Cameron's Conservative Party took a bashing Friday in mid-term local elections, capping a bad month for the government after Britain slid back into recession. However, early vote indications showed Conservative Boris Johnson may hold on to the mayor's job in London in the year of the 2012 Olympics. AFP PHOTO / LEON NEAL (Photo credit should read LEON NEAL/AFP/GettyImages)

  • Two men watch the vote count status on s

    Two men watch the vote count status on screens inside City Hall as results are tallied in the London Mayoral and local elections on May 4, 2012. Prime Minister David Cameron's Conservative Party took a bashing Friday in mid-term local elections, capping a bad month for the government after Britain slid back into recession. However, early vote indications showed Conservative Boris Johnson may hold on to the mayor's job in London in the year of the 2012 Olympics. AFP PHOTO / LEON NEAL (Photo credit should read LEON NEAL/AFP/GettyImages)

  • Local council elections

    Labour leader Ed Miliband in Victoria Square, Birmingham, after Labour made significant gains in the mid-term local elections.

  • Local council elections

    Labour leader Ed Miliband in Victoria Square, Birmingham, after Labour made significant gains in the mid-term local elections.

  • Local council elections

    Labour leader Ed Miliband congratulates Labour Group leader Sir Albert Bore (right) in Victoria Square, Birmingham, after Labour made significant gains in the mid-term local elections.

  • Local council elections

    Edinburgh City Council votes are counted at the Meadowbank stadium, Edinburgh.

  • Local council elections

    Edinburgh City Council votes are counted at the Meadowbank stadium, Edinburgh.

  • Local council elections

    (From left to right) First Minister Carwyn Jones, Cardiff Council leader Heather Joyce and Shadow Wales Secretary Peter Hain celebrate the party's local government election win in the Welsh capital in Queen Street, Cardiff.

  • Local council elections

    Respect Party leader George Galloway at the party's Bradford HQ after they won five seats on the Bradford Council, including that of the Labour leader.

  • Local council elections

    Respect Party leader George Galloway with supporters at the party's Bradford HQ after they won five seats on the Bradford Council, including that of the Labour leader.

  • Local council elections

    Scottish Labour Leader Johann Lamont (right), MP Margaret Curran (left) and Labour leader Gordon Matheson at the SECC in Glasgow, as votes are counted in the Glasgow City Council elections.

  • Local council elections

    Scottish Labour Leader Johann Lamont (left) and Labour leader Gordon Matheson at the SECC in Glasgow as votes are counted in the Glasgow City Council elections.

  • Local council elections

    Scottish Labour Leader Johann Lamont at the SECC in Glasgow as votes are counted in the Glasgow City Council elections.

  • Local council elections

    SNP Leader Allison Hunter (left) and Deputy First Minister Nicola Sturgeon (right) at the SECC in Glasgow as votes are counted in the Glasgow City Council elections.

  • Local council elections

    Leader of the Scottish Conservatives Ruth Davidson (left) with David Meikle at the SECC in Glasgow as votes are counted in the Glasgow City Council elections.