The court in Diyarbakir, the regional capital of the mainly Kurdish southeast, ordered the two men remanded in custody on charges of involvement in extrajudicial killings, said the source, who requested anonymity.

Both men were former militants of the separatist Kurdistan Workers' Party (PKK) who later became informers against the rebel group, which has been fighting a 24-year armed campaign for self-rule.

The arrests came as the local prosecutor ordered a dig near the small village of Karacali, near Diyarbakir, on allegations that two people were buried there after being killed by the intelligence unit of paramilitary troops, JITEM, for alleged links with the PKK.

The claim came from Abdulkadir Aygan, a PKK rebel-turned-informer, now based in Sweden, who earlier this year told the Turkish press that he had worked with JITEM and claimed to have witnessed the murders of some people suspected of links with the rebels.

His remarks led to a prosecutor in Diyarbakir to launch a comprehensive probe in February into allegations that several Kurds were summarily killed in the 1990s, at the peak of the PKK's armed campaign.

Recent digs in the neighbouring province of Sirnak have turned up 20 fragments of bone and pieces of tissue in what the media have dubbed "death pits".

Three other people have been charged in the probe, one of them a colonel who headed paramilitary troops stationed in Cizre town in Sirnak in 1993-1996.

The PKK took up arms for Kurdish self-rule in 1984, triggering a conflict with the Turkish state that has left 44,000 dead, displaced thousands and led to allegations of gross human rights violations by both sides.

Over the past 10 years the bodies of four missing people have been exhumed in the region, the most recent in 2005 by a roadside.