Troubling Anthrax Additive Found; Atta Met Iraqi

W A S H I N G T O N, Oct. 27 -- ABCNEWS has been told by three well-placed and separate sources that initial tests on an anthrax-laced letter sent to Senate Majority Leader Tom Daschle have detected a troubling chemical additive that authorities consider their first significant clue yet.

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An urgent series of tests conducted on the letter at Ft. Detrick, Md., and elsewhere discovered the anthrax spores were treated with bentonite, a substance that keeps the tiny particles floating in the air by preventing them from sticking together. The easier the particles are to inhale, the more deadly they are.

As far as is known, only one country, Iraq, has used bentonite to produce biological weapons.

Just minutes before ABCNEWS' World News Tonight aired this report, White House spokesman Ari Fleischer flatly denied bentonite was found on the letters. Moments later, another senior White House official backed off Fleischer's comments, saying it does not appear to be bentonite "at this point."

The official said the Ft. Detrick findings represented an "opinionated analysis," that three other labs are conducting tests, and that one of those labs had contradicted the bentonite finding. But, the official added, "tests continue."

Fleischer added today that no test or analysis has concluded that bentonite is present in the Daschle anthrax, and "no other finding contradicts or calls into question" that conclusion.

Reading from what he said was a sentence from the report prepared by scientists at Fort Detrick, he told ABCNEWS, "It is interesting to note there is no evidence of aluminum in the sample." Aluminum, Fleischer said, would also be present if bentonite was.

Trademark Additive

While it's possible countries other than Iraq may be using the additive, it is a trademark of Iraqi leader Saddam Hussein's biological weapons program.

"It means to me that Iraq becomes the prime suspect as the source of the anthrax used in these letters," former U.N. weapons inspector Timothy Trevan told ABCNEWS.

In the process of destroying much of Iraq's biological arsenal, U.N. teams first discovered Iraq was using bentonite, which is found in soil around the world, including the United States and Iraq.

"That discovery was proof positive of how they were using bentonite to make small particles," former U.N. weapons inspector Richard Spertzel told ABCNEWS.

But officials cautioned today that even if Iraq or renegade Iraqi scientists prove to be the source, it's a separate issue from who actually sent the anthrax through the mail.