The United States modified on Thursday the number of Americans killed or missing in Asia's tsunami disaster that has claimed over 150,000 lives.

"The number of welfare and whereabouts inquiries we are working at the moments is 2,500. That is down considerably from yesterday and considerably from the beginning of the week, where we started at 6,000," State Department deputy spokesman Adam Ereli said at a news briefing.

The United States said Wednesday that some 3,500 Americans were still unaccounted for in the tsunami-hit areas.

"We are also able today to confirm 17 Americans who have died as a result of this disaster ... The number of presumed dead is down by two, from 20 to 18," Ereli said.

The spokesman said that this is a result of being able to classify one of the presumed dead from Wednesday as confirmed, andthe other decrease is because one person was reported twice under different names, "so we have been able to eliminate one of the names on the presumed dead list."

The United States has been working with governments in the tsunami-hit region, nongovernmental organizations and people in the affected areas in a bid to track people down and verify their status.