Gordon Brown says he will work "night and day" to ensure the "security" and "stability" of the financial system.
His comments come after the government nationalised Bradford and Bingley (B&B) over the weekend, a move which has prompted concerns from the Conservatives who are worried the taxpayer is assuming too much risk.
The prime minister, speaking this morning, said he would do "whatever it takes" to ensure the financial system's stability.
He claimed the government had taken "decisive action" in recent weeks by allowing Lloyds TSB to take over Halifax Bank of Scotland, dealing with "share speculation in the market" and by allowing Spanish banking giant Santander to buy B&B.
"We will work night and day to make sure that Britain can come through this downturn which has started from problems in America," Mr Brown said.
"It is now affecting the whole system, is causing anxiety and insecurity among people in the country and my job is night and day to work for the security of the system."
Mortgage holders, savers, business-owners and "everyone who's got bills to pay" would back his call for stability, he added.