In the port of Izmir, demonstrators hurled Molotov cocktails and stones when police moved in to disperse a crowd carrying banners of the forbidden separatist Kurdish Workers' Party (PKK), NTV television reported.

The gatherings followed overnight clashes between police and Kurdish groups in working-class areas of the city. Molotov cocktails were thrown in one incident but no injuries were reported.

In Istanbul, tens of thousands of people rallied relatively peacefully Sunday, lighting bonfires to signal springtime in the New Year ceremony known as Newroz.

Stones were hurled sporadically at police as some members of the crowd waved the green, yellow and red flags of the PKK, AFP photographers at the scene reported.

Security forces kept a tight grip on the celebration, with 4,500 police backed by armoured vehicles, plus 1,000 soldiers and 500 military police on guard, the Anatolia news agency reported, citing security sources.

Members of Turkey's 12,000-strong Kurdish minority regularly mobilise on Newroz to demand more rights and display their support for the PKK, classed as a terrorist group by Turkey, the European Union and the United States.

Militant leaders of the 12-million strong Kurdish community want an independent state carved from southeastern Turkey.

Some members of the crowd called for the release of PKK leader Abdullah Ocalan, in jail since 1999 for treason. The PKK's struggle against Turkish forces has killed 37,000 people since 1984.

The PKK published on its website a call for Kurds to "rise up" against the Turkish state and to step up the fight against Turkish forces.

In the southern city of Mersin security forces searched participants in Newroz ceremonies to confiscate flags and banners referring to the PKK, an AFP photographer reported.

More than 1,000 police were deployed for the Mersin celebration which drew thousands of people and passed off peacefully. Newroz ceremonies in the city last year had seen clashes between participants and police.