A defector from the former Soviet biological weapons program said in an interview Tuesday that Moscow's Cold War plans for World War III included preparing "hundreds of tons" of anthrax bacteria and scores of tons of smallpox and plague viruses.

The defector, Dr. Kanatjan Alibekov, now known as Ken Alibek, was second-in-command of a branch of the Soviet program and defected in 1992. He said Tuesday that these bacteria and viruses could have been mounted on intercontinental ballistic missile warheads on several days' notice in the early 1980s. Alibek, a 47-year-old native of Kazakhstan, said the Russian military was still running a biological weapons program in 1991, a year after Mikhail Gorbachev ordered it halted.Alibek said he has decided to speak publicly for the first time to fight the spread of biological weapons and to seek absolution for making them. He was introduced to the New York Times by producers of the ABC News program "Prime Time Live," which interviewed him last month and will broadcast the interview on Wednesday night.

Alibek, who works as a private consultant, has written a highly classified study of the Soviet biological weapons program for the U.S. government. He now is offering a unique public description of a weapons program that was for decades one of Moscow's deepest secrets.

Considered by U.S. intelligence officials to be credible about the subjects he knows firsthand - the size and structure of the Soviet biological weapons program from 1975 to 1991 - Alibek is thought to be less reliable on political and military issues he knew secondhand.