WASHINGTON -- The nation's health secretary insisted to skeptical senators Wednesday that federal doctors could quickly contain any bioterrorist attack, and urged Americans not to be panicked by all the preparations for such a possibility.

But even as Tommy Thompson cautioned against stockpiling gas masks or antibiotics, he told Americans to be on the lookout for any mysterious symptoms and see a doctor promptly if they have any.

"People should not be scared into believing they need to buy gas masks. And people should not be frightened into hoarding medicine and food. There is nothing we know of to warrant such actions," Thompson told a Senate Appropriations subcommittee.

But some senators bluntly said they don't believe Thompson's Health and Human Services Department is fully prepared and asked what people should do to guard their health.

"Be very vigilant about your activities and anything suspicious," Thompson responded. "Anything mysterious dealing with your body, get to a doctor ... and ask if their doctor knows anything about bioterrorism."

Thompson, pressed about recent public statements downplaying the threat, insisted his agency could quickly dispatch the proper medical authorities to contain and treat any outbreak from an attack.

"I am absolutely assured we could respond to any contingency," he told senators.

"I just don't believe that," responded Sen. Robert Byrd, D-W.Va., who cautioned against misleading the public.

Thompson acknowledged the health system does have gaps, and said he is seeking $800 million more this year to fill those gaps. Most of the money would go to state and local health departments, to train local physicians and laboratories in recognizing symptoms of anthrax, smallpox and other worrisome agents.

Vaccines against such agents aren't available to civilians today, but are being stockpiled so that if there ever were an attack, people exposed could be vaccinated quickly, Thompson said. His top bioterrorism adviser, Dr. Scott Lillibridge, said the vaccines could cause too many side effects to ever justify routine vaccination against the theoretical risk of an attack.

But Thompson announced the nation's only maker of anthrax vaccine, Bioport Corp. of Michigan, may be able to resume production of doses for the military within six weeks. The company is working to correct repeated violations of Food and Drug Administration safety regulations.

Also, the government has speeded up production of 40 million more doses of smallpox vaccine, to be delivered to a national stockpile of 15 million existing doses by late next year instead of in 2005.