BUENOS AIRES, April 23 (Reuters) - The last de facto president of Argentina's 1976-83 military dictatorship must stand trial on charges he kidnapped children born to parents killed during the country's "Dirty War," a judge ruled on Monday.

The ruling against Reynaldo Bignone marks the first time a member of Argentina's military junta will be tried publicly since military rulers were put on trial in 1985 on charges of human rights abuses.

Bignone and six other high-ranking officers will face prosecution in a case investigating allegations that some children of slain dissidents were handed over to members of the military, federal judge Guillermo Montenegro ruled.

The charges include "taking, retaining and hiding minors and changing their identities," according to the ruling. No formal court date was set.

A government report says 11,000 people either died or disappeared during the military's seven-year crackdown on leftist dissent.

Human rights groups say the number is closer to 30,000.

A former army general, Bignone was the last of four de facto presidents and took power in mid-1982 after Argentina's defeat in the Falklands Islands war.

Among the other officers to face trial are former army chief Cristino Nicolaides, former navy chief Ruben Franco and Jorge Acosta, a former marine.

Following Argentina's dictatorship, many military officers were tried on charges of abduction, torture and execution of suspected opponents of the regime.

They were imprisoned in 1985 and later pardoned in 1990 by then-President Carlos Menem.

In 2005, Argentina's Supreme Court repealed two amnesty laws shielding military officers from prosecution, clearing the way for hundreds to be tried.

Bignone has been held under house arrest in connection with the probe since March. Many of the junta's other top leaders, among them Gen. Jorge Videla and Adm. Emilio Massera, are also under house arrest facing similar charges.

The human rights group Grandmothers of the Plaza de Mayo says it has traced some 90 children of missing political prisoners and reunited them with their biological families.

Last year, Bignone told a local radio station the baby kidnapping charges are "an invention."

AlertNet news is provided by