WASHINGTON - President Bush and financial leaders from nations rich and poor pledged Saturday to intensify their efforts to unblock a frozen financial system before it does more damage to an increasingly shaky global economy.

While there were no concrete offers of new moves, Bush vowed anew that his administration was doing everything possible to halt the biggest market disruptions since the Great Depression. The finance ministers spoke in unusually somber terms about the need for action.

Bush started the day shortly after daybreak with a Rose Garden appearance with finance ministers from the world's richest countries and later made an unexpected evening visit to the headquarters of the 185-nation International Monetary Fund a few blocks from the White House.

With Treasury Secretary Henry Paulson and Federal Reserve Chairman Ben Bernanke, he participated for about 25 minutes in a discussion with the Group of 20, which includes rich countries and major developing nations such as China, Brazil and India.

According to White House spokesman Tony Fratto, Bush acknowledged the problems began in the U.S., with a meltdown of the market for subprime mortgages in the summer of 2007. The president felt it was important to take the rare step of coming to such a meeting because the problems were spreading globally.

"It doesn't matter if you're a rich country or a poor country, a developed country or a developing country -- we're all in this together," Bush said, according to Fratto. "We take this seriously, and we want to work with you."

In response, the G-20 countries issued a joint statement in which the finance officials pledged to work together "to overcome the financial turmoil and to deepen cooperation to improve the regulation, supervision and the overall functioning of the world's financial markets."

The financial turmoil also dominated discussions at weekend's annual meetings of the IMF and World Bank. The IMF strongly endorsed a five-point plan put together a day earlier by the so-called Group of Seven wealthy powers, in which the United States, Japan, Germany, France, Britain, Italy and Canada jointly pledged to use all means possible to prevent major financial institutions from failing and to keep pumping money into the banking system to unfreeze lending and get credit -- the lifeblood of the economy -- flowing again.

"The depth and systemic nature of the crisis call for exceptional vigilance, coordination and readiness to take bold action," the IMF said in its joint statement. That statement, in an unusual move, repeated verbatim all of the commitments made in the G-7 statement that had been released on Friday.

"There is a resolve that this crisis will be resolved, that no tools will be spared to address this issue," Egypt's finance minister, Youssef Boutros Ghali, chairman of the IMF's policy panel, told a news conference late Saturday.

In his Rose Garden appearance, Bush made a plea for nations work together to address the crisis, avoiding the go-it-alone trade strategies that worsened conditions during the Great Depression.

"In an interconnected world, no nation will gain by driving down the fortunes of another. We are in this together. We will come through it together," Bush said, flanked by representatives from G-7 nations, the IMF, World Bank and European Union. "There have been moments of crisis in the past when powerful nations turned their energies against each other or sought to wall themselves off from the world. This time is different."

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