Boris Johnson has repeated his support for giving amnesty to illegal immigrants, days after David Cameron dismissed the idea as "terrible".
The Tory mayor of London told LBC Radio on Tuesday morning that people who had been in the country for 12 years or more should be granted the right to stay - a policy position he has taken before.
"This was something that came up in 2010 and every single party leader turned my machine guns on me, he said. "We effectively have it [amnesty], if you've been here for more than 12 years I'm afraid the authorities are no longer prepared to pursue you, they give up."
Asked if that meant he supported an amnesty he said: "Why not be honest about what is going on. Yeah, absolutely."
"You've got people who are living here, ultimately you've got to reflect a reality," he said. "Otherwise they are not engaged in the economy, they are not being honest with the system, they are not paying their taxes, it is completely crazy."
However Boris said this did not mean the government should not be "much tougher" in policing the border to ensure fewer people were allowed to enter the country illegally in the first place.
On Friday Cameron slapped down one of his most loyal backbench MPs after he suggested an amnesty would be an effective way for the Conservative Party to win ethnic minority votes.
Nadhim Zahawi, who is tipped for promotion to ministerial office in the next reshuffle, said not only would amnesty be politically advantageous for for the Tories - but would it boost the economy.
"Economically, a one-off amnesty would make sense," he said. "There are an estimated 570,000 illegal immigrants in the UK; this vast hidden economy cheats the Treasury out of billions while undercutting the pay and conditions of low-income workers. At a time of austerity, moving these people into the legitimate economy has obvious attractions."
At the 2010 general election the Conservatives only won 16% of the ethnic minority vote. Zahawi, the MP for Stratford-on-Avon MP and a co-founder of the polling company YouGov, said "unless we act now this electoral penalty will only get worse."
However the prime minister shot down the plan within hours. "It's not one we are going to implement. It would send a terrible signal as Britain as a soft touch," he said.