Valuing truth over the right to privacy, Argentina's Congress has authorized the forced extraction of DNA from people who may have been born to political prisoners slain a quarter-century ago _ even when they don't want to know their birth parents.

Human rights activists hope the new law will help find about 400 people stolen as babies, many from women who were kidnapped and gave birth inside clandestine torture centers during the 1976-1983 dictatorship. Thousands of leftists disappeared in what became known as the "dirty war" against political dissent.

Others see the new law as unacceptable government intrusion, legalizing the violation of a person's very identity. And as written, it could have much broader implications, enabling DNA to be sought from anyone whenever a judge determines the evidence to be "absolutely necessary."

Children of the "disappeared" were often given to military or police families considered loyal to the military government. Some have grown up not even knowing they were adopted until activists or judges announced efforts to obtain their DNA.

The project of the Grandmothers of the Plaza de Mayo, close allies of President Cristina Fernandez, was approved by a 58-1 vote of the Senate on Wednesday. Since it has already passed in the lower house, it will become law once it is published in Argentina's official bulletin.

Recovering their grandchildren has been a priority for the group since they first began demonstrating in front of the presidential palace in 1977, carrying pictures of their disappeared relatives.

DNA technology has helped them identify 98 of 500 children they believe were born in prison or kidnapped as infants.

Using survivors' testimony, documents from birth families and adoption records, they have persuaded some judges to seek DNA from suspected victims of the "dirty war." But courts have sometimes ruled that a child's right to privacy outweighs a grandmother's right to know.

The new law legalizes the extraction of "minimal amounts of blood, saliva, skin, hair or other biological samples" to determine identity. If a person refuses to provide a sample, a judge can issue a warrant for genetic material from a hairbrush, toothbrush, clothing or other objects.

"It's an absolute invasion of the right to biological privacy," constitutional lawyer Gregorio Badeni told The Associated Press. "No one has the right to know what I have inside my body. That belongs only to me. I can give it up voluntarily, but no one can obligate me to deliver it."

Estela de Carlotto, who heads the grandmothers group, disagrees.