Two former leaders during Argentina's military rule have been found guilty of overseeing the systematic theft of babies from political prisoners.

It is thought as many as 400 babies were taken from their leftist parents in detention and placed with families aligned to the ruling military.

Jorge Videla and Reynaldo Bignone are both in their 80s and are already serving lengthy sentences for crimes committed under military rule between 1976 and 1983.

Both have now been found guilty of devising the plan to steal detainees' babies.

The judge said Videla was being sentenced to the maximum sentence of 50 years while Bignone was given a 15 year term.

Their trial surrounded the kidnapping of 35 children.

As the verdict concluded cheering could be heard from hundreds of people who had gathered outside.