PENTAGON EXPANDS SEARCH FOR VETERANS NEAR IRAQI BLAST.

Byline: Philip Shenon The New York Times

The Pentagon said Tuesday that it would notify 20,000 veterans of the 1991 Gulf War - four times more than previously announced - that they might have been exposed to nerve gas and blistering agents when a battalion of U.S. combat engineers blew up an Iraqi ammunition depot that was later determined to have contained chemical weapons.

The announcement greatly expands the search for Gulf War veterans who might have suffered exposure to clouds of chemical agents released from the Kamisiyah ammunition depot in southern Iraq in March 1991, shortly after the war.

The department announced last month that it would contact 5,000 troops who were within 25 kilometers, or about 16 miles, of the sprawling depot when large portions of it were destroyed March 4 and March 10, 1991. The search was expanded Tuesday to an estimated 20,000 veterans who were within 50 kilometers, or about 31 miles.

``Right now, this is our best guess of the people who could have come even close to very minimal exposure,'' said Kenneth Bacon, the department's chief spokesman. He explained that the area to be examined for possible chemical exposure had been expanded from 25 kilometers to 50 kilometers because ``we decided to be safe, to go double that.''

He warned, however, that the estimate of the number of veterans who might have been exposed to the chemicals could grow yet again if a computer model under review by the CIA shows that the chemicals might have wafted over other areas of the Persian Gulf where American soldiers were deployed.

``Depending on what we learn from the CIA model after it's been reviewed,'' he said, ``we may decide we have to notify more people.'' The agency's computer model of weather patterns and other scientific data is not expected to be released publicly for several weeks.

Thousands of Gulf War veterans have complained of a variety of ailments, including chronic fatigue, chronic nausea and joint pain, which are sometimes known collectively as Gulf War syndrome.

The Pentagon also disclosed Tuesday that U.S. troops might have blown up a third site within the Kamisiyah arsenal March 12, raising at least the possibility of another, later chemical exposure. Officials said combat logs suggest that hundreds of rockets were destroyed in a third blast, although there is no evidence to suggest that they definitely contained chemical agents.