The prosecution is seeking a life sentence with no chance of parole for 23-year-old Erdal Polat on seven counts of premeditated murder for each of the victims killed in the January 3 bombing in Diyarbakir.

The indictment describes Polat as a member of the separatist Kurdistan Workers' Party (PKK) who was ordered by his superiors to carry out attacks in retaliation for Turkish strikes on rebel camps in neighbouring Iraq since mid-December.

It says Polat parked the bomb-laden car on a street in the centre of Diyarbakir and set it off as an army bus was passing by with several dozen soldiers on board on their way to a military facility.

In Friday's opening hearing, Polat acknowledged that he was a PKK member, but said he had only bought the car used in the attack and handed it over to two other Kurdish rebels.

"I do not know what happened after that. I never went to the crime site," he told the court.

Polat risks two other counts of life imprisonment for separatism and a hand grenade attack against a police station in Diyarbakir in December.

Eleven other suspects, most of them Polat's relatives, face up to 15 years in jail for "deliberately and willingly aiding the terrorist organization."

The January 3 attack killed seven civilians -- six of them teenagers attending classes at a nearby private school -- and left 68 people injured, about half of them military officers.

The PKK, listed as a terrorist group by Ankara and much of the international community, apologised for the attack and put the blame on Kurdish militants acting without the approval of the leadership.

The rebels have been threatening retaliation as the Turkish army, aided by US intelligence, has carried out several air strikes and a week-long incursion into northern Iraq to hit PKK camps since December 16.

The PKK has been fighting for self-rule in Turkey's southeast since 1984 in a bloody conflict that has claimed more than 37,000 lives.