The truce, first announced in March, had been due to expire on Wednesday.

The decision to extend it had been taken in anticipation of a "roadmap for a democratic solution" by Abdullah Ocalan, the jailed leader of the rebel Kurdistan Workers' Party (PKK), expected in August, senior PKK commander Murat Karayilan told the Firat news agency.

"In order to lay the ground for the roadmap... we have decided to extend the non-action period until September 1," he said. "Within this period, our forces will not take any military action apart from fighting in self-defence that could be forced upon us."

He said the PKK "places great importance on the roadmap and already officially declares that it will stand behind it."

Ocalan has been serving a life sentence for treason on a prison island in northwestern Turkey since 1999.

Karayilan charged that Ankara's declared desire to resolve the conflict lacked "sincerity" and accused the government of seeking to weaken the PKK.

If Ankara "insists on policies of annihilation, I would like to emphasise that our movement is stronger than ever and in a position to defend itself," he said.

Ankara has never formally recognised PKK's unilateral truces and military operations against the rebels have continued.

The PKK, which took up arms for self-rule in Turkey's Kurdish-majority southeast in 1984, is listed as a terrorist group by Ankara and much of the international community.

The conflict has claimed about 44,000 lives.

In May, President Abdullah Gul urged swift measures to end the conflict, stressing that "increasing democratic standards" was the way to resolve it.

His appeal revived debate on how the Kurdish issue should be resolved amid media speculation that the government may consider fresh steps to win over the Kurdish community and encourage the PKK to lay down arms.

Eager to boost its EU membership bid, Ankara has in recent years granted the Kurds a series of cultural freedoms, but failed to draw up a specific strategy to convince the PKK to end its armed struggle.

The government rules out dialogue with the PKK and has rejected calls to consider a general amnesty for the rebels.