U.S. President Barack Obama says it is time to overhaul the rules governing the nation's financial sector. The Obama administration says that while it wants tighter regulations, it has no plans to nationalize banks.

One day after a speech to the nation on his economic plan, President Obama weighed in on the need to set new rules for America's ailing financial sector.

"We now know from painful experience that we can no longer sustain 21st century markets with 20th century regulations," said President Obama.

The president spoke after meeting with his top economic advisors and leading members of the two Congressional financial committees.

Mr. Obama said the process of drafting the necessary legislation to put tougher financial regulations in place starts now. He said the aim is clear.

"Strong financial markets require clear rules of the road - not to hinder financial institutions, but to protect consumers and investors and ultimately to keep those financial institutions strong," he said.

He said new regulations must promote openness and transparency. He said they must be comprehensive and promote accountability.

Congressional leaders say there is no hard timetable for completing the legislation, insisting that it is more important to do the job right than to do it fast.

But President Obama makes clear he would like to have a regulation plan in hand when he goes to London for the April 2 summit of the world's leading developed and emerging economies.

"As we work to set high regulatory standards here in the United States, we have to challenge other countries around the world to do the same," he said.

The president acknowledged that drafting the necessary legislation will be difficult. But he predicted that Democrats and Republicans will be able to come together on this issue.

Representative Spencer Baucus, the top Republican on the House of Financial Services Committee, agrees.

"This is too important to fail," he said. "And it is too important for partisanship."

The White House push for financial services reform comes amidst worries that the administration might go further and nationalize troubled banks.

But in congressional testimony on Wednesday, central bank chairman Ben Bernanke played down the possibility of a government takeover.

"A nationalization to my mind is when the government seizes the bank, zeros out the shareholders and begins to manage and run the bank," he said. "And we don't plan anything like that."

At the same time, the Treasury Department announced that the nation's biggest banks would be granted immediate access to more of the federal government's $700 billion financial rescue fund.