Argentina's Senate passed a bill Thursday that could see hundreds of people take mandatory tests to determine whether their parents were among the thousands who disappeared under military rule.

DNA tests will now be mandatory for any person believed to be among the estimated 500 children born to opponents of the government who were taken and given to those deemed loyal to the authorities during Argentina's "dirty war" against leftists.

The tests will be administered -- voluntarily or not -- without however - causing prejudice or indecency - according to the bill.

If the person refuses to give a blood sample, authorities will now be allowed to take a hair sample or even seize the individual's toothbrush or underwear.

Human rights activists say some 30,000 Argentines "disappeared" during the 1976-83 military dictatorship, and fewer than 100 of the babies born during their mothers' captivity at clandestine detention centers have discovered their true identity.

Nine children of the "disappeared" have already been identified through DNA tests using non-blood samples.

The legislation, adopted with support from the right-wing opposition, was proposed by the government of center-left President Cristina Kirchner with support from the Inter-American Commission on Human Rights and the         - Grandmothers of the Plaza de Mayo. -

The group represents children who were separated from their families during the military dictatorship. Some 98 stolen children have uncovered their identity since 1983.

Since Nestor Kirchner -- the current president's husband -- came to power in 2003, Argentine authorities have sought to bring to justice those accused in the wave of disappearances.