Turkish authorities had rejected a Kurdish demand to mark Navroz on Sunday as it was a holiday and had declared Wednesday as the official day for the celebrations.

Police fired tear gas and high pressure water hoses to prevent thousands of Kurds from gathering at the main square in Diyarbakir, the capital of the Kurdish-majority south, an AFP correspondent said.

The unrest spread to nearby areas and several cars were torched, the correspondent said.

But the crowd of more than 40,000 pressed on despite the police action and assembled at the city centre to mark Navroz by jumping over flames, as per tradition, and dancing.

Many wore clothes sporting the colours of the banned Kurdistan Workers' Party (PKK) -- green, red and yellow.

The PKK took up arms in Kurdish-majority southeastern Turkey in 1984, sparking a conflict that has claimed about 45,000 lives. It is labelled a terrorist group by Ankara and much of the international community.

Turkey's Anatolia news agency reported several arrests in Diyarbakir and said the Kurds threw firebombs. It said a policeman had his arm broken in the melee while an elderly man had head injuries after being hit by stones.

Security sources said two men were arrested after an assault rifle was found in their car.

Many demonstrators demanded the release of PKK leader rebel chief Abdullah Ocalan, who was jailed for life in 1999,

In Istanbul, police prevented Kurdish groups from gathering at a venue where the country's main Kurdish party had organised festivities. A group of Kurds stoned the police, who had set up barricades, Anatolia said.

Police responded with water cannon and tear gas, the agency said.

Navroz celebrations are traditionally used by Turkey's Kurdish minority to press for greater rights and profess its allegiance to the PKK.

The bloodiest Navroz in Turkey occurred in 1992, when some 50 people were killed by security forces in the Kurdish-dominated southeast.