Pressed by surprised lawmakers who were not sure if they had heard him right, he repeated that several tiimes.

"Iron your letters," he said, adding that a microwave oven was not as good as an iron and that including moisture was essential because spores could survive dry heat.

For large amounts of mail, in big cities or postal distribution centers, he recommended setting up portable gamma radiation units to sterilize letters. "This problem could be solved," he said.

Alibek repeated the advice of many other experts that people should not buy gas masks. But he said that if his biotech company and two others doing similar work got "significant funding," they probably could bring to market new antiviral drugs that would work against several potential bioterror weapons within two years. "We've had interesting results with animals," he said.