In a weekend summit, leaders from the world's biggest economic powers ordered a clampdown on reckless market behavior, including steps they said would help prevent the next credit crisis.

The question now is whether, in their haste to address a futurecrisis, the leaders of the Group of 20 may have inadvertently taken steps that could worsen the current one. "This is a big signal to everybody to clamp down on their banks to tighten lending standards," said Simon Johnson, a former chief economist at the International Monetary Fund. "The last thing you want to do in a global credit crunch is go around and basically tell people to tighten, tighten, tighten."

As part of a lengthy to-do list, G-20 leaders told financial regulators to demand that banks create bigger liquidity cushions, assess their risk-managementpractices and boost capital requirements for certain risky investing practices. The group set a March 31 deadline for the measures, while putting off major regulatory decisions.

Mr. Johnson, now a business professor at the Massachusetts Institute of Technology, said such moves would encourage banks to hoard capital and would make sense once the crisis has passed. But leaders, he noted, were eager to take action.

President George W. Bush, U.K. Prime Minister Gordon Brown, Chinese President Hu Jintao, French President Nicolas Sarkozy and the other G-20 leaders vowed to take the necessary steps -- government spending programs, tax cuts or interest-rate reductions -- torestart a global economy teetering on the edge of recession.

The leaders embraced a renewed effort to unblock global trade talks and promised they will refrain from using commercial barriers to protect their own industries. "We agreed on the importance of rejecting protectionism," Mr. Brown said. "It is the first time that a meeting of world leaders has instructed ministers to come to an agreement and I think we will see an agreement in the next few weeks."

The initiative could provide an early test for President-elect Barack Obama, who has campaigned as a trade skeptic, but may be reluctant to reject a major round of international trade talks as one of his first moves in the international stage.

The meeting also underscored a split Mr. Obama will have to reconcile. The U.S., China and Canada, among others, have been more cautious about new cross-border regulations than their European counterparts, especially the French.