Ocalan made the appeal through his lawyers Thursday from his prison cell following an upsurge in rebel violence that has raised tensions in Turkey at a time when stability is crucial for its bid to join the European Union.

"A ceasefire is done between states. It is not something for the terrorist organisation," Erdogan told the private Samanyolu television channel late Thursday, referring to Ocalan's outlawed Kurdistan Workers' Party (PKK).

"The terrorist organisation must lay down its arms. That is what we are waiting for to restore peace in the (Kurdish) region," Erdogan said.

This was no surprise, Turkish officials having ignored four previous truces proclaimed by the PKK, the longest of which lasted from 1999 to 2004.

"The first and foremost principle is to entirely eradicate this terrorist group. The PKK should lay down its arms unconditionally ... and surrender to Turkish justice," Edip Baser, coordinator of the struggle against the PKK, said Friday.

Kurdish activists, however, warned against a hasty rejection of Ocalan's move, urging Ankara to seize any opportunity for a lasting solution to the 22-year conflict.

"The country needs this chance at peace," Sirri Sakik, spokesman for the main Kurdish party, the Party for a Democratic Society (DTP), told AFP.

"If this situation is handled well by all concerned -- the politicians, the army and the PKK -- we could obtain an end to the hostilities."

In Diyarbakir, the main city of the Kurdish-majority southeast, Ocalan's call raised expectations for an end to years of bloodshed; a powerful bomb blast blamed on the PKK killed 10 people there earlier this month.

"We believe the PKK will heed Ocalan's appeal and we hope the truce will mark the beginning of a process in which arms will be laid down for good," human rights activist Selahattin Demirtas told AFP.

"The prime minister should not undermine this process in advance and should instead encourage all developments that can help end the conflict," he said.

Pointing to the ravaged economy of the region, local business leader Sah Ismail Bedirhanoglu said: "We want an end to violence. Any contribution is welcome, whoever makes it."

Ocalan has been serving a life sentence for separatism and treason since 1999 in the northwestern prison island of Imrali, where he is the sole inmate.

His appeal came on the heels of change in the Turkish military hierarchy, with General Yasar Buyukanit, perceived as more of a hardliner than his predecessor, becoming chief of the general staff and renewing the army's vow to hunt the PKK down to the last man unless they surrender.

There was no immediate reaction from the PKK to Ocalan's appeal as fighting on the ground continued, with officials in Sirnak province saying two rebels were killed there Thursday in a gunbattle with the security forces.

The PKK's military branch is based in the mountains of neighboring northern Iraq -- a source of friction between Ankara, Washington and Baghdad. Its political leaders live in exile in Western Europe.

Ocalan is believed to retain significant influence over the PKK, which took up arms for independence in the southeast in 1984. The conflict has claimed more than 37,000 lives.

The group, classed as a terror organisation by Turkey, the EU and the United States, abandoned its independence plans after Ocalan's arrest in Kenya in 1999 and called a truce that lasted for five years.

Ankara in the meantime undertook a series of reforms to improve the lot of the country's estimated 10 to 15 million Kurds -- out of a total population of 73 million -- as part of efforts to align with EU norms.