David Cameron has apologised for mistakes his party made on the economy, among them not warning about the extent of the UK's debt crisis.
In a speech, the Tory leader said he was "sorry" he had got some things wrong and opposition members as well as ministers should admit failings.
The Conservatives have called on Gordon Brown to apologise for policy failures at home over debt and bank regulation.
Treasury minister Stephen Timms accused Mr Cameron of "hypocrisy".
Prime Minister Gordon Brown says the financial crisis began abroad and needs global action. He has said he will not "shy away" from decisions he took over the past 11 years but has said the Tories do not understand the nature of the financial crisis, accusing them of a "do nothing" approach.
In a speech to the Birmingham Chamber of Commerce, Mr Cameron said politicians needed to admit past mistakes if they were to build public trust and lead the economic recovery.
"I am sorry we have got some things wrong," he said.
"We were right to call time on government debt but should we have said more about banking debt, corporate debt? Yes we should have done.
Saying sorry was the "easy bit", Mr Cameron said, adding that it was more "difficult" for politicians to say where they had gone wrong.
"It's that that needs to take place in order to build trust with the public so that we can get this economy out of recession and into recovery," he said.
There are other areas of economic policy where I look back now and think we would have done it differently if we had the time again
The Conservatives have been pressing the government to admit the recession was not "imported from abroad" and that ministers allowed debt levels to get out of control at home and failed to regulate banks properly.
In response, Chancellor Alistair Darling said ministers "clearly have to accept responsibility...for the things that are good and not so good" done by government.
He told the BBC he had long argued that the bank regulatory system needed to be "strengthened and improved".
And Treasury Minister Stephen Timms said: "This is hypocrisy from David Cameron, not that long ago his policy commission was actively pushing for the complete deregulation of the mortgage market."
He accused the Conservatives of failing to back government schemes to help people at risk of repossession and the bringing forward of £3bn investment for new projects to boost the economy.
The Lib Dems said the Tories should focus on offering solutions to the country's economic problems rather than "being content to snipe from the sidelines".
During the speech, Mr Cameron said the Tories could have done more to warn about excessive debt levels in certain areas of the economy.
"Do I believe we did enough to warn about the rising levels of corporate debt, banking debt and borrowing from abroad? No.
"And there are other areas of economic policy where I look back now and think we would have done it differently if we had the time again.
"For example, while we warned that it was wrong and complacent to claim that boom had been abolished ... we based our plans on the hope that economic growth would continue."
The Conservatives should have made the case that the UK economy was "broken" much earlier, Mr Cameron added.
BBC political correspondent Carole Walker said Mr Cameron acknowledged failings by previous Conservative governments by saying some "fundamental" weaknesses in the economy pre-dated Labour's period in office.
Mr Cameron claimed Gordon Brown was unable to make the "clean break with the past" needed, as he is in denial about the nature of the problems facing the economy.
"He believes none of Britain's problems are home-grown. He thinks that a fundamentally sound economy has been hit by an external financial juggernaut, that Britain is just the innocent victim of a banking crisis that 'came from America'," the Conservative leader said.
Ministers are preparing for the G20 summit of leading economies in London next month which they hope will agree reforms to bank regulation and measures to boost economic demand.
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