ANKARA, Turkey (AP) _ Leftist inmates on Friday freed the last 17 prison guards they held after authorities agreed to witness the hostage release and to assess damage at the prison, a human rights activist said.

Marxist inmates at seven Turkish prisons had seized 74 guards Sunday to protest the storming of an Ankara prison by security forces earlier that day. The raid killed 10 inmates.

Inmates at six prisons began freeing their hostages early Friday after authorities promised an independent inquiry into Sunday's raid.

But inmates at Istanbul's Umraniye prison refused to release their 17 hostages.

``They were demanding that authorities be present when the hostages were released and that they make an assessment of any damage caused to avoid problems in the future,'' said Nazmi Gur, of the independent Human Rights Association, which was involved in some of the negotiations.

Authorities said Sunday's raid was ordered following reports inmates were digging an escape tunnel. Prisoners said it was a pretext for soldiers to break up wards that prisoners from leftist and Kurdish groups often run like political indoctrination centers. Some prisoners in the wards have cellular phones that they use to coordinate their actions with inmates in other prisons.

The inmates had made the hostage release conditional on an end to the government policy of breaking up the wards by transferring inmates to other prisons. It was unclear if the government agreed.

Human rights groups and leftist inmates have frequently accused prison guards of torturing prisoners, particularly those from Kurdish and leftist groups that oppose the state.