US President George W. Bush told world leaders Friday that the financial crisis would not be resolved `overnight` at the start of a summit here to discuss the problems gripping the globe.

`This problem did not develop overnight and it will not be solved overnight but with continued cooperation and determination it will be solved,` he said as leaders from the G20 group of countries held a working dinner at the White House.

The summit, billed as a first in a series, comes amid growing evidence that the worst international financial crisis in generations is taking a heavy toll on economies around the world.

Bush renewed his call for free and open markets, laid out five objectives for talks on Saturday and said the meeting would be one in a series.

`Free market capitalism has been an engine of prosperity, progress, and social mobility in economies all over the globe,` he said.

`All our nations must reject calls for protectionism, collectivism, and defeatism in the face of our current challenge.`

Discussions on Saturday, to take place behind closed doors at the National Building Museum, will focus on `understanding the causes of the global crisis, reviewing the effectiveness of our responses thus far, (and) identifying principles for reforming our financial and regulatory systems.`

Bush said they would also include `launching a specific action plan to implement those principles, and reaffirming our conviction that free market principles offer the surest path to lasting prosperity.`

The US president also hailed coordinated action by countries since the beginning of the crisis.

`Thanks in large part to these decisive measures, global credit markets are beginning to thaw. Businesses around the world are regaining access to essential short-term financing,` Bush said.

The crisis blew up last year when the US housing market went into reverse but worsened in September. As banks in the United States and Europe booked losses from their exposure to the US housing market, they stopped lending to each other, sparking a credit crunch.

Created in 1999, the Group of 20 (G20) countries accounts for 85 percent of the world economy and about two-thirds of its population.

Its members are the United States, Germany, Japan, France, Italy, Britain and Canada, the European Union, Argentina, Australia, Brazil, China, India, Indonesia, Mexico, Russia, Saudi Arabia, South Africa, South Korea and Turkey. Spain and the Netherlands have also been invited.