It will be the Labour Party's fault if Scotland votes for independence next week, Sir John Major has said.
The former Tory prime minister said Tony Blair's decision to devolve power to a Scottish parliament had been the "high road to separation".
Major's attack cracks the pro-Union united front David Cameron, Ed Miliband and Nick Clegg will today attempt to present to Scots as they travel north to campaign against independence.
Writing in The Times today, Major said while he was opposed to the break-up of the UK, "no one should weep" for Labour should it happen.
He said: "We should not forget that, throughout the 1980s and 1990s, Labour connived with nationalist opinion in demonising the Conservatives and, by implication, the English. They are doing it still, and have fed a divisive narrative that has bitten deep, ignoring the revolution in Scottish living standards brought about, in large part, by Conservative policies."
In his column Major said he hopes Scotland will not vote to break away when it votes on September 18 and warned Britain would be "damaged", leading to a decline in its role on the international stage including within the European Union and United Nations.
Cameron pleaded with Scotland not to rip apart the Union today as he issued a warning that independence is a "leap into the dark" from which there is no going back.
In an article for the Daily Mail, the prime minister set out some of the United Kingdom's greatest achievements - including the Scottish enlightenment, the abolition of slavery and defeating fascism - to highlight "what is at stake" on September 18.