Unrest 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 hold 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 in the fighting while many demonstrators were taken into custody, Anatolia said.

Kurds demonstrated 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 of mistreatment on Sunday.

The unrest however spread Monday to Diyarbakir as Erdogan arrived in the city 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 controlled 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 garbage.

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

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

The PKK, blacklisted as a terrorist organisation by the European Union and the United States as well as by Turkey, picked up arms for self-rule in the mainly Kurdish east and southeast in 1984, sparking a conflict that has claimed some 44,000 lives.