The heirs to Argentina’s most powerful media empire have been ordered to take DNA tests that could establish whether they were part of a forced adoption scheme during the country’s darkest era.

Civil rights campaigners claimed that the real parents of Marcela and Felipe Noble Herrera, whose mother controlled the country’s biggest newspaper, were abducted and murdered by the last dictatorship during its “Dirty War” against Left-wing dissidents.

The pair were adopted in 1976 by Ernestina Herrera de Noble, the director of Grupo Clarín, Argentina’s dominant media group. Mrs Herrera de Noble – whose late husband, Roberto, set up Clarín, Latin America’s best-selling newspaper — claimed that the babies were left abandoned on her doorstep one night.

Her claim has been challenged by the Grandmothers of the Plaza de Mayo, a civil rights group trying to locate 500 children of the thousands of dissidents who disappeared under the dictatorship between 1976 and 1983.

Mrs Herrera de Noble, 84, whose husband died in 1969, was childless and the Grandmothers group alleges that her two children were taken from political prisoners who gave birth while in custody in secret torture centres.

Children of the “disappeared” were often given to military or police families considered loyal to the government. Some have grown up not even knowing they were adopted until activists or judges announced efforts to obtain their DNA. On Tuesday, Marcela and Felipe Noble Herrera, both 33, complied with a judge’s order and gave samples at the Legal Medical Department, a federal forensics agency, according to their lawyer, Jorge Anzorreguy.