The United States Wednesday appealed for decisive action by Asian governments and relief organizations to prevent the sexual trafficking or other abuse of orphans and others left homeless by the December 26 earthquake and tsunami disaster.

The State Department says it has no firm figures on the number of tsunami orphans or other displaced persons who have fallen prey to traffickers.

But it says there are enough credible reports to conclude that there is as real danger of this. It is appealing to all concerned parties including Asian governments and relief organizations working there to take decisive action to prevent such abuse.

There have been press accounts of, among other things, children of persons killed or missing in the disaster being taken away from makeshift camps for displaced people, and the rape of women there.

At a news briefing, State Department Deputy Spokesman Adam Ereli said the U.S. officials are appalled by such reports and horrified that thousands of children orphaned by the disaster are vulnerable to exploitation by criminal elements.

He said the State Department has sent out an alert to non-governmental organizations involved in disaster relief, warning of the potential for human trafficking amid what is still a chaotic situation in affected areas.

?The concern is that, at this particular moment, in the immediate aftermath of the disaster, when there is a lot of confusion, that it is important to put in place measures that prevent potential abuse and potential exploitation of a confused and relatively unregulated situation,? he said.  ?I'm not speaking as a general policy or for further in the future. But right now we're concerned that circumstances lend themselves to abuse. And proper action should be taken to prevent that.?

Spokesman Ereli commended Indonesia for moving swiftly to halt international adoptions of tsunami orphans in the face of potential abuse.

He said U.S. officials are offering guidelines to relief workers and volunteers in the region to minimize the risk of human trafficking.

He said these include registering displaced-persons camp residents, especially women and children, and ensuring proper security for the camps.

Mr. Ereli also told reporters the State Department has declared 20 Americans as missing and presumed dead from the Asian disaster. This is in addition to 16 U.S. citizens already confirmed dead.

He said officials were still seeking information on the welfare and whereabouts of some 3,500 Americans who were believed to have been in the region when the earthquake and tsunami struck.

Working around-the-clock, State Department officials have this week narrowed the list of such cases down from about 6000.  They stress that those still being sought are not necessarily disaster victims.