President Bush signed legislation on Wednesday aimed at encouraging the development of drugs and vaccines to negate the impact of attacks using biological and chemical weapons.

The $5.6 billion, 10-year Project BioShield program expands public- and private-sector research incentives to develop treatments, antidotes and vaccines that would otherwise not find a viable commercial niche.

“We will rally the great promise of American science and innovation to confront the greatest danger of our time,” Bush said during a signing ceremony in the White House Rose Garden.

Bush penned his name to the law on the same day his staff was to be briefed on the final report of the commission investigating the Sept. 11, 2001, attacks. Bush will receive a copy of the report upon its release on Thursday.

The BioShield legislation will encourage more research and will also basically guarantee a market by buying and stockpiling the new drugs and vaccines to treat or protect people against such diseases as anthrax, smallpox or the plague, or against such toxins as ricin.

Without such assurances, the private sector would be reluctant to invest millions in products that in a best case scenario would never be needed.