Some 200 backers of the Kurdish Workers' Party (PKK) took to the streets of Istanbul's working-class Okmeydani quarter, shouting slogans in support of PKK leader Abdullah Ocalan, imprisoned since his conviction in 1999.

They threw stones and petrol bombs at police, who then used tear gas and water cannons to break up the demonstration.

The CNN-Turk television station reported on similar clashes in Bagcilar, on the outskirts of Istanbul and known for its large Kurd population.

The Turkish army has threatened an intense campaign against the PKK in the Kurdish-dominated southeast. The army launched a limited-scope operation against rebels in northern Iraq at the beginning of the month.

The Kurdish conflict in Turkey has killed more than 37,000 people since the beginning of the PKK insurrection in 1984.