Brandishing Ocalan portraits and chanting anti-government slogans, about 3,000 people -- among them a popular Kurdish MP and the local mayor -- marched in Diyarbakir, the largest city of the Kurdish-majority southeast.

Police warned the crowd to disperse on grounds the demonstration was unauthorised.

The protestors -- some wearing masks -- pelted security forces with stones and the police responded with tear gas, water cannons and paint bullets.

As a police helicopter flew overhead, security forces surrounded the local headquarters of the Kurdish Democratic Society Party, which organised the event, and chased protestors through the neighborhood.

Fifteen people, among them eight policemen, were injured and 42 demonstrators detained, the Diyarbakir governor's office said.

There were also violent protests in Hakkari province, where demonstrators set bonfires and barricaded streets, shouting slogans in favour of Ocalan and his separatist Kurdistan Workers' Party (PKK), Anatolia news agency reported.

At least four people, among them two boys, were detained, the agency said.

One person was injured during unrest in the town of Idil, in neighbouring Sirnak province.

In nearby Nusaybin, security forces detained 15 people after coming under a hail of stones that left the local police chief and three other officers injured, Anatolia said.

Riot police used tear gas against protestors also in the Mediterranean city of Mersin, home to a large community of Kurdish migrants, where many children counted among a crowd hurling stones at the security forces, Anatolia said.

Violent Kurdish demonstrations are frequent on the anniversaries of Ocalan's capture on February 15, 1999.

Ocalan, 59, is the founder of the PKK, listed as a terrorist organisation by Ankara and much of the international community. He led the group's bloody campaign for self-rule in the southeast from 1984 until his arrest.

Ocalan was captured in the Kenyan capital Nairobi after being forced to leave the Greek embassy. He had taken refuge there for several days while on the run, after leaving his long-time safe haven in Syria in October the previous year.

Four months later, a Turkish court condemned him to death for treason, but the sentence was commuted to life in 2002 after Ankara abolished capital punishment as part of reforms to align with European Union norms.

For many Kurds, however, Ocalan remains a national hero. His condition in the prison island of Imrali in the Marmara Sea, where he is the sole inmate, is closely followed by activists.

The PKK's armed campaign has provoked a heavy-handed response by the Turkish military, with the conflict claiming about 44,000 lives since 1984.

In its bid for EU membership, Ankara has granted the Kurds cultural freedoms, but Kurdish activists argue the conflict cannot be resolved if the government fails to make peace with the PKK.