Flanked by the two former presidents, Bush urged US citizens and businesses to give cash to charities already helping countries pummelled by the strongest earthquake in four decades and the resulting tidal waves.

"I ask every American to contribute as they are able to do so," the president said. "In this situation, cash donations are most useful, and I've asked the former presidents to solicit contributions both large and small."

His comments came after US Secretary of State Colin Powell, in Asia to put a US face on relief efforts, said he was bringing no new pledge of US aid amid charges that Washington's early response to the disaster was tight-fisted.

In a hastily announced joint appearance with the former presidents, Bush countered such criticism, saying: "The greatest source of America's generosity is not our government, it's the good heart of the American people."

Clinton and the elder Bush will seek more money from private US citizens and businesses, which have already provided millions of dollars in donations to charities responding to the disaster, said the president.

He did not specify a target amount.

The international community has pledged a total of two billion dollars for tsunami relief, including 500 million from Japan and 350 million from the United States, but delivery of badly needed material has been snagged by logistical bottlenecks at key airports.

The president, the elder Bush and Clinton together visited the embassies of Indonesia, Sri Lanka, India and Thailand -- the four hardest hit countries -- to pay their respects and sign books of condolences.

"The devastation in the region defies comprehension," Bush said as the official death toll from the massive earthquake and tidal waves that hit Indian Ocean shorelines a week ago reached 145,161 Monday.

"We mourn especially the tens of thousands of children who are lost. We think of the tens of thousands more who will grow up without their parents or their brothers or their sisters. We hold in our prayers all the people whose fate is still unknown," said Bush.

Later, in remarks to newly elected US lawmakers, Bush said that he would make providing aid to afflicted countries "the first order of business" when the US Congress reconvenes later this month.

White House spokesman Scott McClellan told reporters that Bush intended to give money to the effort, but did not specify an amount. The president himself made no reference to his personal plans in his remarks.

In an interview with CNN, the elder Bush disputed the notion that his son was stepping up relief efforts in order to shore up Washington's image abroad, saying: "It's not the goal."

But "it always helps America when countries that aren't as rich and powerful as we are think we're pulling for them. They get it," he said.

Clinton also defended Bush's response, telling CNN: "I think right now we are where we need to be, and we shouldn't be looking back, we should be looking forward."

The US Geological Survey said the earthquake west of the Indonesian island of Sumatra measured 9.0 on the Richter scale, making it the largest quake worldwide in four decades.

Indonesia has borne the brunt of the December 26 catastrophe, with a health ministry official putting the country's dead at 94,081 with entire coastal villages disappearing under the wall of water.

The figure could rise substantially. The health ministry has cautioned that there could be 100,000 deaths in Aceh and North Sumatra.

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