Ocalan, leader of the armed separatist Kurdistan Workers' Party (PKK), asked for a retrial in January after the European Court of Human Rights (ECHR) ruled last year that his trial was unfair.

The final decision is up to an Ankara court dealing with serious criminal and terrorism-related cases.

A possible retrial could unleash fierce public anger in Turkey, where Ocalan is widely seen as public enemy number one among many Turks.

Pro-PKK Kurdish youths went on the rampage and clashed with security forces in several cities in the southeast and in Istanbul last week, resulting in 15 deaths, and hundreds of injuries and arrests.

Ocalan, 57, who launched a bloody rebellion in southeast Turkey in 1984, was condemned to death in 1999 for treason, but his sentence was commuted to life imprisonment in 2002 after Turkey abolished capital punishment as part of efforts to align with European Union norms.

Ocalan's demand for a review of his sentence poses a legal challenge to the government because current laws do not allow for his retrial, although Ankara is under pressure to comply with the rulings of the Strasbourg-based ECHR.

The ECHR ruled in May that the court that convicted Ocalan was not impartial because it included a military judge during part of the trial, and because Ocalan and his lawyers lacked sufficient time and opportunity to prepare their defense.

Ankara has said it will respect the ruling, but the authorities have so far failed to say how they will proceed.

Officials have said a possible retrial will seek to correct procedural flaws but cannot result in a lighter verdict for Ocalan, whose PKK is blacklisted as a terror group by Ankara, the EU and the United States.

The Kurdish conflict in Turkey has claimed some 37,000 lives since the PKK took up arms for self-rule in the predominantly Kurdish southeast in 1984.