The prime minister signalled his support for radical change in the way banks are regulated.
The prime minister has again called for a major reform of the way the financial system works.
In a speech in to Labour's National Policy Forum, Gordon Brown called for a return to "responsibility" among financial firms. Light-touch regulation and bonus-hungry banks have been blamed by observers for causing the credit crunch - which has in turn pushed much of the world into recession.
The International Monetary Fund recently predicted that global growth would sink to an unprecedentedly low of 0.5 percent in 2009, as millions of people lost their jobs and consumer confidence collapsed around the world. Britain was predicted to suffer one of the very worst annual downturns, with output sinking by almost three percent across the year.
Another respected economic group, the NIESR, has also predicted a 2009 economic contraction of up to three percent. However, the government's last estimate, made in November 2008, forecastd a decline of around one percent.
Mr Brown said: "Our task must be nothing less than to rebuild a financial system where it has failed, and then to create an economy in which banks are no longer serving themselves but are serving the public of this country."
Referring to the light-touch regulators, he added: "Some came to believe that we should sacrifice the value of being fair to that of laissez-faire … Some of the practices now being discovered in our banks are not only unacceptable, they are indefensible and they have got to be cleaned up now."
Responding, shadow chancellor George Osborne told the BBC that the prime minister should bear some blame for the way the financial system was overseen prior to the credit crunch. "This all happened on Gordon Brown's watch as a result of his polices," he commented.
"That makes him part of the problem, not the solution."
