"There is substantial information that the eight soldiers are in PKK hands," Democratic Society Party chairman Ahmet Turk told the Anatolia news agency, referring to the separatist Kurdistan Workers' Party.

"The youths should be handed over to their families," Turk said. "When the conditions are right, we will make certain efforts."

The PKK pledged it would not harm the soldiers it said were captured during an ambush on a patrol near the Iraqi border on Sunday, in which 12 troops were killed.

The PKK on Tuesday released what it said were photographs of the captive soldiers.

The Turkish army has confirmed that eight soldiers are missing, increasing pressure on the government for military action in northern Iraq, where the PKK takes refuge.

The DTP, whose detractors accuse it of being a tool of the PKK, holds 20 seats in the Turkish parliament.