"The PKK cannot be eliminated by violence, it will strengthen its numbers, the fight will intensify. We are warning you," the agency quoted Ocalan as telling his lawyers at the jail where he is held in Imrali, northwestern Turkey.

The PKK leader also called on Ankara to implement a "democratic plan", apparently referring to autonomy demanded by the PKK for Turkey's Kurdish population concentrated mainly in the southeast, Firsat reported.

Ocalan said that rebels could be convinced to withdraw from Turkey and eventually disarm if their demands for self-rule were met by the Turkish government.

Ocalan was jailed for life in 1999 after a death sentence for treason was commuted following the abolition of capital punishment.

His comments followed reports by security forces that four Turkish soldiers and a PKK fighter were killed in clashes late Friday near Kupelidag in southeastern Sirnak province, close to the Iraqi border.

Turkey has been massing troops along the Iraqi border in recent weeks to prevent PKK fighters entering Turkey from several bases in northern Iraq.

The Kurdish conflict in Turkey has claimed some 37,000 lives since the PKK took up arms for self-rule in the southeast in 1984. The PKK has stepped up its attacks since a 1999 ceasefire broke down in 2004.