By Heba Saleh
BBC correspondent in Cairo
An independent Algerian human rights organisation says it has found a mass grave containing as many as 200 bodies.
Thousands are said to have disappeared after being arrested
It said the pit held the remains of people who disappeared after being arrested by a state-backed militia.
The Algerian League for the Defence of Human Rights also said it had managed to identify one of the bodies as that of a man who disappeared in 1996.
Human rights groups believe at least 7,000 people have disappeared in the past decade after being arrested.
The Algerian League for the Defence of Human Rights said it secretly opened the mass grave in the western province of Relizane after being alerted to its presence by local people.
The group said it removed clothing that was later identified by a family from the region as belonging to a man who disappeared in 1996.
His son said he had been taken away by a militia operating under the supervision of the local administration.
This is the first time that information has emerged about the fate of one of the thousands of people who disappeared in Algeria after arrests by the security services or their civilian allies.
Despite regular demonstrations in Algiers by the mothers of the disappeared, the Algerian Government has yet to shed light on a single case.
The majority of the disappearances took place in the mid-1990s. That was the peak of the armed confrontation between the Algerian state and its Islamist opponents.
The conflict started in 1992 after the Algerian army interrupted elections to stop an Islamist party from winning.
Human rights groups say both sides in the conflict committed atrocities against civilians, including kidnappings and forced disappearances.