Ken Clarke, the minister without portfolio, has warned his government colleagues over their "reckless" and "threatening" statements about Britain's relations with the European Union.

He said he did not understand the theory expounded by some of his colleagues that Britain's economic difficulties were caused by the EU.

David Cameron has said he will seek a "fresh settlement" of Britain's relations with the EU after the election and the education secretary, Michael Gove, is reported to have said that the UK should use the threat of possible withdrawal as a weapon in negotiations.

"To start threatening, throwing into the air our relationship with the outside world, with the global economy, would I think be very reckless," Clarke told the Daily Telegraph. "I frequently say that to several of my colleagues: there seems little point in opening up the debate at the moment about our membership of the European Union."

Despite the problems in the eurozone, Britain's economic difficulties were caused by "the folly of bankers, the uselessness of regulators and the weakness of government", Clarke said. "The idea that somehow the present problems are caused by Britain's membership of the European Union is a theory that I can't quite follow."

Although better-than-expected growth of 1% in the third quarter of 2012 was announced earlier this week, Clarke said it was too early to be certain the economy is bouncing back. He said married couples should not expect the tax relief proposed by the Conservatives in their 2010 manifesto which promised a transferable tax allowance that could be worth £150 a year to couples where one spouse stays at home.

Clarke, a former chancellor, said there was "a long hard road" ahead and that the tax allowance was not a government commitment.

"It would be absolute folly to turn around and say it will all be fine by Christmas," he said. "Anybody who says we are absolutely certain we are bouncing back to strong growth is being very optimistic.

"We never committed ourselves to married couples' tax by the end of the parliament. I'm married, I'm not counting on it. I don't remember anyone promising that kind of thing."