The Liberal Democrats have criticised the Conservatives - accusing their Coalition colleagues of attempting to pinch one of their policies and claim it as their own.

The row erupted after the Tories released posters boasting of an "income tax cut" for 25 million people.

The raise in the income tax threshold was featured on the front page of the last Lib Dem manifesto.

The Liberals insist the tax cut is one of the key ways it can prove it has helped ­ordinary people while in government with the Conservatives. Last week LibDem leader Nick Clegg said he wanted to increase the level again, from the current £10,000 to £12,500.

The Liberals yesterday attempted to ridicule the Conservatives, releasing footage of Tory leader David Cameron saying he was opposed to the rise in the personal income threshold during the 2010 television debates, saying that he did not think that the country could afford the tax cuts.

A senior LibDem source said there had been no warning from their Coalition partners of the posters.

He said "imitation is the sincerest form of flattery", but if the Conservatives attempted to claim credit for the policy during the next Westminster elections, due in 2015, it would backfire.

"We will win (that fight)," he said.