The warning came in the wake of renewed clashes between Kurdish militants and the army and a deadly attack on an election convoy of Turkey's ruling Islamist-rooted Justice and Development Party (AKP), which officials blamed on rebels.

Meeting in Diyarbakir, the main city of the Kurdish-majority southeast, an umbrella Kurdish organisation condemned military operations against the rebels and the detention of activists, dismissing AKP pledges of reconciliation as "deception."

"If the process continues like that, we will be considering many options, including not participating in the elections" on June 12, a statement said.

"Our determination to build a democratic, autonomous Kurdistan and to organise legitimate resistance against the attacks will continue."

Turkey's main Kurdish party, the Peace and Democracy Party (BDP), was among the signatories of the statement.

Last week, the army killed seven militants from the Kurdistan Workers' Party (PKK), which has waged a 26-year separatist war against Ankara, in clashes in east Turkey despite a truce the outlawed group had declared in August as a gesture of good will.

Prime Minister Recep Tayyip Erdogan, whose party enjoys solid popularity among less militant Kurds, reacted angrily to the latest warning.

"This is a method of challenge which is not democratic," Anatolia news agency quoted him as saying.

"The BDP is trying to achieve its goals with the support of terrorists," he said, referring to the PKK, which Ankara lists as a terrorist group.

Tensions rose after gunmen ambushed an AKP convoy on a mountain road near the northern city of Kastamonu Wednesday, killing a policeman and wounding another before fleeing into the forest.

The assailants hurled a hand grenade and opened fire on a police car escorting an AKP bus returning from a rally attended by Erdogan.

The prime minister had left Kastamonu by helicopter.

Kastamonu Governor Erdogan Bektas said on Thursday intelligence showed that a group of PKK militants was active in the region, adding that, "we know the same group has taken responsibility for the (convoy) attack."

He did not elaborate.

The attack may have been retaliation for last week's killing of the seven PKK militants, a senior police official told the mass-selling Hurriyet daily.

"We were expecting such attacks ... We had issued warnings that the PKK would step up attacks in the election period," he said.

Northern Turkey is not a region where the PKK is usually active, but officials have warned that the group is seeking a foothold there.

Despite a series of reforms broadening their rights, Kurds are frustrated that a government initiative to seek dialogue with the PKK, announced last year, has so far been inconclusive.

Aiming to cajole the PKK into permanently laying down arms, officials have held discreet meetings with jailed PKK leader Abdullah Ocalan, who retains influence over the rebels.

But Ocalan's lawyers, who regularly meet him in prison, say the talks have failed to achieve any tangible progress.

The PKK took up arms in 1984, sparking a conflict that has claimed some 45,000 lives.