More than 30,000 were killed or went missing

The decision on Friday upholds a ruling by another federal judge earlier this year that Argentina's amnesty legislation contradicted constitutional guarantees protecting human rights.

BBC South America correspondent Tom Gibb says that if the ruling remains unchallenged, it could open the way for hundreds of further cases against more than 1,000 military personnel.

Human rights groups estimate that the military killed or "made disappear" about 30,000 people in Argentina in a campaign against leftwing revolutionary groups between 1976 and 1983.

The two former policemen are accused of kidnapping handicapped Chilean man Jose Liborio and his Argentinean wife, Jerturides Halaczik, both of whom subsequently disappeared.

Laws overturned

Their baby daughter was also kidnapped and then given to a military officer to be brought up.

Witnesses say that after being tortured, the two parents were taken to be thrown into the Atlantic from a helicopter.

The two accused had received amnesty under two separate laws passed in 1986 and 1987.

The 1976 coup marked the beginning of the Dirty War

The so-called "full stop" law prevented any new cases from being filed after 1986, and the "due obedience" law then exonerated military personnel if they were following orders.

But earlier this year federal judge Gabriel Cavallo ruled that both laws should not apply, as they contradicted constitutional guarantees of human rights.

Now this ruling has been upheld in a unanimous decision by three other judges, emphasising that eliminating the laws was "not an option but an obligation".

Human rights groups hope this could set a precedent for other Latin American countries, in some of which United States intelligence services were directly involved.