Police moved in on the 2,000-strong group in the city of Van when some demonstrators chanted slogans in favour of Abdullah Ocalan, the jailed leader of the Kurdistan Workers' Party (PKK) separatist rebels, the NTV news channel reported.

The demonstration was organized by the country's main Kurdish political movement, the Democratic Society Party (DTP), which is accused by Ankara of colluding with PKK rebels.

Prosecutors on Friday launched proceedings to ban the DTP, saying that the party had become a "base for activities which aim at the independence of the state and its indivisible unity" through its links with the PKK.

The DTP, which holds 20 seats in the 550-member parliament, rejects charges of links with the rebels. It has come under fire for refusing the brand the PKK a terrorist group, as Ankara does, and for voicing sympathy for the rebels.

More than 37,000 people have been killed since 1984 when the PKK picked up arms for self-rule in Turkey's mainly Kurdish east and southeast.

Last month, the Turkish government won parliamentary authorization to order troops into northern Iraq if necessary to strike at bases the PKK uses as a springboard for attacks on Turkish targets.

Turkey has subsequently massed an estimated 100,000 troops and military equipment on the border with Iraq. The United States and Iraq are opposed to any cross-border strike.