SAN FRANCISCO - Six veterans who say they were exposed to dangerous chemicals, germs and mind-altering drugs during Cold War-era experiments filed a federal lawsuit against the CIA, Department of Defence and other agencies on Wednesday.

The veterans say they volunteered for military experiments as part of a wide-ranging programme started in the 1950s to test nerve agents, biological weapons and mind-control techniques, but were not properly informed of the nature of the experiments.

They blame the experiments for poor health and are demanding the government provide their health care. They also want the court to rule that the program was illegal because its administrators failed to get their consent.

Marie Harf, a CIA spokesman, declined to comment on the lawsuit, which seeks class action status on behalf of all participants allegedly exposed to harmful experiments without their knowledge. Vietnam Veterans of America, a veterans advocacy group, is also a plaintiff.

The suit, filed in San Francisco, alleges that at least 7,800 US military personnel served as volunteers to test experimental drugs such as LSD at the Edgewood Arsenal near Baltimore, Maryland, during a programme that lasted into the 1970s, and that many others volunteered for similar experiments at other locations.

'In virtually all cases, troops served in the same capacity as laboratory rats or guinea pigs,' the lawsuit states.

The suit contends that veterans were wrongfully used as test subjects in experiments such as MK-ULTRA, a CIA project from the 1950s and '60s that involved brainwashing and administering experimental drugs like LSD to unsuspecting individuals. The project was the target of several congressional inquiries in the 1970s and was tied to at least one death.

Ms Harf said that MK-ULTRA 'was thoroughly investigated and the CIA fully cooperated with each of the investigations.' The plaintiffs say many of the volunteers' records have been destroyed or remain sealed as top secret documents. They also say they were denied medals and other citations they were promised for participating in the experiments.

They are not seeking monetary damages but have demanded access to health care for veterans they say were turned away at Department of Veterans Affairs facilities because they could not prove their ailments were related to their military service.

In 1988, the Justice Department agreed to pay eight Canadians a total of US$750,000 (S$1.1 million) to settle their lawsuit alleging they suffered psychological trauma from CIA-financed mind-control experiments that included the use of LSD. -- AP