Gordon Brown hit out at David Cameron today for issuing "ridiculous" warnings that the UK could effectively go bankrupt.
Speaking ahead of economic figures expected to put the country formally in recession, the Prime Minister insisted the Government was using "every weapon at our disposal" to combat the financial crisis.
He also suggested he was not getting enough credit for his leading role in tackling the global problems.
Mr Brown told BBC Radio 4's Today programme that the current crisis was "totally different" to anything seen before, because it was not driven by high inflation and wages.
"We are fighting this recession with every weapon at our disposal," he said.
The Government was putting in place the "foundation stones" for when the recovery arrived, according to the PM. Asked whether the upturn would come this year, he insisted that was dependent on international co-operation.
Tory leader Mr Cameron warned yesterday that Britain could soon have to go to the International Monetary Fund for cash, repeating the action of James Callaghan's Labour Government in 1976.
But Mr Brown dismissed his comments as "ridiculous behaviour".
"I think this is ridiculous behaviour on behalf of opposition parties. The situation in Britain is this: that we have low public debt, we have low inflation, wages are under control."
The premier lashed out at prominent investors such as hedge fund boss Jim Rogers, who have been giving dire assessments of the prospects for UK plc and sterling.
"If you think we are going to build our policy around the comments of a few speculators who want to make money out of Britain then you are very, very wrong indeed," he said.
"The decisions we take about the future of the economy are based on what is right for Britain."
Mr Brown said that previously the whole of economic policy had been focussed on "how to control inflation".
The Government had recognised there had been a danger of "institutional failure in the banking system" and acted to bolster national regulation, he insisted. But the global financial crisis was "completely new territory".
"What we did not see, nobody saw, was the possibility of markets failure."
Mr Brown said the Government had "analysed" the financial crisis, and come up with "very precise" solutions.
"We have had to rethink so many of our policies," he said. "I hope we have been ahead (of other countries) in doing so."
Mr Brown went on: "We have had 10 years of growth in this country that no other government has had in any period of previous history."
"We're dealing actually with a global financial crisis with a determination and confidence about how we can get through it."
He added: "Every country is facing these problems and I believe we are doing it with a great deal more determination than a lot of people are giving the credit for."
The premier refused to give any estimate for the taxpayer's total commitments from bailouts of the financial system, but stressed that Northern Rock had paid back £15 billion to the public purse and £1 billion had been received from banks in fees for "insuring" liabilities.
He also insisted the Conservatives had not come up with any viable solution apart from what the Government was trying to do.
"These (things) are what you have to do when the banking system fails," Mr Brown said. "What is the alternative?"