All three men are members of the Democratic Society Party (DTP), the main political movement of Turkey's Kurdish minority.

A court in Diyarbakir, the central city of the predominantly Kurdish southeast, charged DTP provincial chairmain Hilmi Aydogdu with "inciting hatred" and jailed him pending trial, judicial officials said.

In the eastern city of Van, DTP provincial chairman Ibrahim Sunkur and another party activist, Abdulvahap Turan, were arrested late Thursday for allegedly supporting separatist Kurdish rebels fighting the Ankara government, Anatolia news agency reported.

The authorities acted after documents and banners of the outlawed Kurdistan Workers' Party (PKK) as well as banned books by its jailed leader Abdullah Ocalan were seized in the city's DTP office.

Aydogdu, meanwhile, was arrested after the media quoted him as saying this week that Turkey's Kurds would "consider a Turkish attack on Kirkuk as an attack on Diyarbakir."

Ankara has issued harsh warnings over the future of the ethnically mixed, oil-rich city of Kirkuk in northern Iraq, which the Iraqi Kurds want to incorporate into their autonomous region.

The city is also home to Arabs and Turkish-backed Turkmens.

Aydogdu's remarks provoked a harsh reaction here at a time when Iraqi Kurds are accused of supporting the PKK, whose militants have long taken refuge in the mountains of the Kurdish autonomous region in northern Iraq.

The Turkish army chief said last week that Iraqi Kurds provided the PKK with explosives for bomb attacks across the border in Turkey.

Ankara has threatened a military incursion into northern Iraq to crack down on rebel bases if Baghdad and Washington fail to act against the group, listed as a terrorist organisation by Turkey and much of the international community.

Ankara fears that Iraqi Kurds may break away from Baghdad and embolden the PKK to step up its campaign in Turkey, which has already resulted in more than 37,000 deaths.