Violent protests also greeted Prime Minister Recep Tayyip Erdogan in Diyarbakir, the largest city of the predominantly Kurdish southeast, where he arrived later for a one-day visit.

"One person is dead," a police officer told AFP by telephone from the town of Dogubayazit, without giving other details.

The clashes erupted when the protestors, shouting slogans in favour of Ocalan and his separatist Kurdistan Workers' Party (PKK), attempted to stage a march, refusing police orders to disperse, the Anatolia news agency reported.

The demonstrators pelted officers with stones while police fired shots in the air and used tear gas and water cannons against the group, the agency said.

It was not immediately clear how the victim, a man, died, but unconfirmed reports said he was shot.

A police officer was also injured while many demonstrators were detained, Anatolia said.

Kurdish protests began across Turkey at the weekend after Ocalan's lawyers reported he had been assaulted by a guard and threatened with death in his cell on the prison island of Imrali, in the northwest, where he is the sole inmate.

Justice Minister Mehmet Ali Sahin firmly denied the allegations Sunday, but the unrest spread to Diyarbakir as Erdogan arrived in the city Monday to attend the opening of the academic year at the local university and inaugurate a medical centre.

At least 20 people were detained as hundreds of Kurdish protestors gathered in the streets, chanting pro-PKK slogans, pelting the police with stones and hurling petrol bombs at schools.

The police, reinforced with special riot units from neighbouring provinces, used water cannons and tear gas to disperse the crowds as armoured vehicles patrolled the streets and helicopters flew over the city.

Most shops remained closed -- a traditional Kurdish protest method against the government -- as public bus services in downtown areas were cut and the municipality, held by the Kurdish Democratic Society Party, did not collect the rubbish.

Erdogan blamed the violence on the PKK, listed as a terrorist group by Ankara and much of the international community, saying the rebels sought "to sabotage" government efforts to boost the rights and prosperity of the sizeable Kurdish community.

"Despite all the provocations of the terrorist organisation, Turkey will make concessions neither from security nor freedoms and human rights," he said in a speech at Dicle University.

"Turkey's European Union process is continuing," he said, referring to the country's bid to join the European bloc, which has resulted in broader Kurdish cultural freedoms.

Erdogan assured the public TRT broadcaster would soon launch a special Kurdish-language channel, a government pledge since March.

Similar reports about Ocalan's prison conditions have stirred anger in the past among Turkey's Kurds, many of whom view the rebel chief as a hero.

The unrest coincides with intensified Turkish military operations against the PKK -- both inside Turkey and in neighbouring Iraq, where the rebels take refuge.

Arrested in Kenya in February 1999, Ocalan, 60, was condemned to death but the sentence was commuted to life imprisonment in 2002 after Turkey abolished capital punishment.

The PKK picked up arms for self-rule in east and southeast in 1984, sparking a conflict that has claimed some 44,000 lives.