Repeatedly invoking the threat of terrorism, the Senate on Wednesday unanimously approved a $5.6-billion, 10-year initiative to encourage private industry to develop vaccines and drugs that would protect Americans from biological, chemical or nuclear attacks.

If terrorists have access to anthrax, smallpox, botulism toxin, plague or Ebola virus, said Sen. Judd Gregg (R-N.H.), "there is no question they will use it. And they will use it in a place where people gather to go about their daily lives."

The Senate vote came more than two years after anthrax-filled letters caused five fatalities, changed the way mail was inspected and delivered, and highlighted the nation's vulnerability to bioterrorist attacks.

President Bush, who on Wednesday praised passage of the bill as "another important step in winning the war on terror," proposed Project Bioshield in his 2003 State of the Union address. The House passed a bill, 421-2, last summer, but the legislation stalled in the Senate over the technical concerns of a handful of lawmakers.

A small group of molecules has been shown to inhibit a deadly toxin associated with inhalational anthrax, a discovery that could lead to new ways of treating the disease, researchers said on Monday.

Scientists at Harvard Medical School and Beth Israel Deaconess Medical Center here said the finding might help in the development of a drug that when combined with antibiotics, could treat inhalational anthrax when antibiotics alone were no longer effective.

A new drug could foil bioterrorists' attempts to engineer antibiotic-resistant anthrax. The drug could also make a quick hand-held detector for checking contaminated sites, say US scientists.

The anthrax used in last October's US mail attacks was treatable, but future strikes could be worse. "Any sophisticated terrorist could easily engineer strains to be resistant to antibiotics," says anthrax researcher Stephen Leppla of the National Institutes of Health in Bethesda, Maryland.