Updated

The death toll of Americans from the tsunami more than doubled Wednesday, to 36, as the State Department announced 20 other U.S. citizens were presumed dead. Thousands more are missing.

Nineteen of the newly listed victims were in Thailand and the 20th in Sri Lanka, two of the hardest-hit countries, deputy spokesman Adam Ereli (search) said.

Eyewitnesses and others on the scene provided the information that led the department to presume the 20 Americans had died, Ereli said. "In each of these cases there is a specific reason to believe that the individual was in harm's way at the time of the tsunami," he said.

The Pentagon, meanwhile, expanded its contribution to recovery efforts. The Army sent several helicopters to distribute supplies and dispatched about 100 people from bases in South Korea and the United States to deal with a variety of medical and logistics needs.

The Army also is sending four mortuary affairs teams from Fort Lee, Va., to help recover human remains and identify victims. Engineering support teams from the Army will help plan reconstruction.

President Bush (search), who has pledged $350 million in U.S. aid to help disaster victims, has personally contributed $10,000 to the relief effort, his spokesman said Wednesday.

In a speech on legal issues in Collinsville, Ill., Bush praised the U.S. military for its "heroic work" and urged Americans to continue to open their wallets.

"The most important contribution a person can make is cash," Bush said. "There's huge generosity here in America."

Eleven days after the earthquake and tsunami, some 2,900 Americans still have not been located, a U.S. official said Wednesday. The figure earlier in the day was placed at 3,500.

The State Department has received 26,000 inquiries and was able to resolve about 18,000 of them by Monday, Ereli said. Sharp reductions followed quickly.

Citing the privacy of families, Ereli declined to identify the 36 Americans, except to say none was a U.S. official.

"We at the State Department will spare no effort and leave no stone unturned to answer the questions that we are receiving from Americans about the welfare and whereabouts of their loved ones and friends," he said.

The State Department has shied away from estimating how many Americans might have perished.

On Tuesday, Ereli said there were 16 known dead, eight in Thailand and eight in Sri Lanka (search), a count he repeated on Wednesday.

As part of the U.S. government's efforts to identify American victims of the tsunami, officials have asked Thai and Sri Lankan authorities for the names of Americans who entered those countries prior to Dec. 26, when disaster struck.

Ereli said the Thai government has provided such information and that Sri Lanka was expected to do the same.

The spokesman said the administration "is horrified that thousands of children, orphaned by this disaster, are vulnerable to exploitation by criminal elements who seek to profit from their misery."

And, he said, the U.S. government was trying to help in the return and repatriation of children.

Secretary of State Colin Powell (search), who is on a trip to the area, is understood to have urged department officials to be more informative about American victims.

At least 60 Germans died in the disaster — the highest official toll of foreigners so far — and another 1,000 remain missing.

Sweden has reported 52 of its citizens were killed and 1,903 remain missing.

Church bells rang out across Europe on Wednesday and shoppers, mass transit and stock exchanges paused for three minutes of silence in tribute to the victims.