Ocalan, 57, who launched a bloody Kurdish 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 democracy norms.

Ocalan's demand poses a legal challenge to the government because current laws do not allow for his retrial, but Ankara is under pressure to comply with the rulings of the ECHR, lawyer Ibrahim Bilmez said.

"They will have to amend the laws," he told AFP.

Recommending a retrial, the ECHR ruled in May that the Turkish court that convicted Ocalan was not impartial because it included a military judge during part of the trial and because Ocalan and his lawyers were denied the required time and facilities to prepare their defense.

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

Officials have said a possible retrial will seek to correct procedural flaws but that it would not result in a lighter verdict for Ocalan, whose Kurdistan Workers' Party (PKK) is blacklisted as a terror group by Ankara, the EU and the United States.

A possible retrial could unleash fierce public anger in Turkey, where the rebel leader is still a figure of hate for many.

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.

Ocalan told his lawyers he had sent an application for a retrial to an Ankara court when they last met him on January 18 at the prison island of Imrali, northwestern Turkey, where the PKK leader is the sole inmate, Bilmez said.