World leaders emerging from a financial summit in Washington pledged to continue taking "urgent and exceptional" action to revive the global economy Saturday, calling for increased cooperation and regulation to prevent the crippling crisis from repeating itself.

President Bush, speaking after the meeting, stressed that the emergency summit was only a "first step," and that others would be scheduled — but praised the measures given the go-ahead so far.

He said the United States could have gone into a depression worse than the Great Depression without the steps already taken.

Nearly two dozen foreign leaders convened Saturday in an attempt to steer their countries away from recession and at the same time draft plans to prevent future financial meltdowns.

Bush said the participants agreed to modernize their regulations by making financial markets more "transparent and accountable."

He urged other nations to resist erecting trade barriers, and pledged that the United States would also make good on its aid commitments to developing countries despite the financial stresses.

"I thought this was a very successful summit," Bush said.

In a joint statement from the group of 20 nations released Saturday afternoon, those countries' leaders said: "We must lay the foundation for reform to help to ensure that a global crisis, such as this one, does not happen again."

The countries are "determined to enhance our cooperation and restore global growth," they said.

The lengthy statement spelled out six immediate steps that would be taken.

The nations pledged to continue "vigorous efforts" to stabilize the financial system; recognize the importance of "monetary policy support"; "use fiscal measures to stimulate domestic demands"; help developing nations gain access to financing especially through the International Monetary Fund; encourage the World Bank and other banks to fully support developing nations; and ensure that organizations like the IMF and World Bank have "sufficient resources" to help countries overcome the crisis.

Bush said the world's top economies will also take "a fresh look at rules that govern market manipulation and fraud."

In a global climate marked by increased government intervention and rescue packages, Bush said at the start of the meeting that he was glad the partner nations were reaffirming the principles of "open markets and free trade."

According to one diplomatic source, the summit participants were also discussing ways to boost international coordination of stimulus packages.

A thorny issue, however, is whether all nations should pledge to enact government spending plans to stimulate their economies. The leaders supported the benefits of that approach, but stopped short of a commitment for all to act at the same time, as some Europeans had favored.

The plan endorses an early warning system for problems such as the speculation frenzy that fed the U.S. housing bubble. It calls for the creation of "supervisory colleges" of financial regulators from many nations to better detect risky investing and other potential problems.

It will be up to finance ministers to flesh out the details to put such changes in place by the end of March, in advance of the next summit on April 30, when Barack Obama is president.

"Our nations agree that we must make the financial markets more transparent and accountable," Bush said.

Leaders backed efforts to improve international monitoring of markets and bolstering rules about how companies value their assets, a weakness seen as partly responsible for the crisis at hand.

The leaders pledged to "use fiscal measures" to energize individual countries' economies "as appropriate." They recognized the importance of the Federal Reserve and other central banks to order interest rate reductions to help cushion the economic fallout.

"We have reached important conclusions today about trade, about financial stability and about the expansion of our economies," British Prime Minister Gordon Brown said.

Under the glare of an intense political and public spotlight, presidents and prime ministers needed to be careful not to let the talks become a blame game, which could further roil the fragile markets.

French President Nicolas Sarkozy was heartened that leaders could come together on a plan for action despite diverse interests from individual nations.

While the plan would boost oversight of fragile financial markets, it fell short of the sweeping tough new set of regulations or ambitious regulatory overhauls that some Europeans initially wanted.

"These are difficult talks," acknowledged Brown, who had taken a lead in pushing for a global coordination of country-by-country economic aid plans.

In his weekly radio address, Bush said he's confident that the developed and developing countries involved in the talks can return their economies "to the path of growth and vitality."

"Nations around the world have responded to this situation with bold measures, and our actions are having an impact," Bush said. "It will require more time for these improvements to fully take hold and there will be more difficult days ahead, but the United States and our partners are taking the right steps to get through the crisis."

The Bush administration, however, has reacted coolly to a second U.S. stimulus plan and opposes a bailout of the teetering U.S. auto industry. Democrats are pushing for aid to Detroit automakers amid reports that the biggest one, General Motors Corp., could be forced into bankruptcy by the end of next month.

Not far from the summit at the stately National Building Museum, a handful of protesters carried neon yellow signs that read: "Money for people's needs, not bankers' greed" and "Money for jobs, not for war and occupation."

The World Bank president, Robert Zoellick, is among the international finance leaders who welcomed the more inclusive mix of countries — beyond the wealthiest nations — at the summit. Brazil's president, Luiz Inacio Lula da Silva, said, "Emerging economies have to be taken into consideration in today's globalized world."

Japan's prime minister, Taro Aso, urged China and others to help increase the International Monetary Fund's $250 billion bailout pool for struggling nations hit by the crisis. Japan on Friday said it was ready to put in as much as $100 billion.

The crisis broke out in the United States around August of last year.

Mortgage investments soured with the housing market's collapse and the fallout quickly spread to other countries. Banks and other financial companies suffered huge losses and foreclosures skyrocketed. The troubles crimped auto and student loans and locked up lending for many consumers and businesses worldwide.

Although Obama stayed away from the summit, he designated two representatives — former Secretary of State Madeleine Albright and former Republican Rep. Jim Leach of Iowa — to meet with leaders on the sidelines.

Besides the United States, the participants are: Argentina, Australia, Brazil, Britain, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Spain and Turkey.

Other than Spain, those countries — plus the European Union — make up the Group of 20 industrialized and developing economies, or G-20. The group accounts for roughly 90 percent of the global gross domestic product, which measures the value of goods and services produced worldwide.

FOX News' Bret Baier, Peter Barnes and The Associated Press contributed to this report.