BBC Ankara Correspondent Chris Morris reports

Osman Ocalan, the brother of imprisoned PKK leader Abdullah Ocalan, said the PKK would from now on try to operate as a political organisation

"We are laying down our weapons, never to take them up again," he said, in a statement broadcast by a pro-Kurdish satelite channel.

"The PKK will never fight again."

The statement on behalf of the PKK leadership added that the group would "try to prevent others from taking up arms, should they try to do so".

Withdrawal

The rebels announced last week that they had begun withdrawing from Turkey in line with a call by Abdullah Ocalan to end the armed struggle.

The Turkish army has fought a bitter 15-year war with the PKK

Osman Ocalan said the rebels had intended to complete their withdrawal within five days, but had so far been able to pull out only a quarter of their forces as a result of the Turkish army's operations and the difficulty of the terrain.

About 20 rebels had died in fighting with Turkish troops during the operation so far, he said, adding that Turkey too had lost troops.

But he said the withdrawal would be complete by the end of the year and his fighters were complying with a cease-fire order.

He did not reveal where the forces would go, but the Turkish Government says the PKK has bases in northern Iraq, Iran and Syria.

Death sentence

Osman Ocalan also warned of a possible backlash should his brother's death sentence be carried out.

"This does not mean we will start the war again," he said. "But if he is hanged, we will not be able to control the situation."

"PKK members will not listen to the PKK leadership if Ocalan is killed."

Abdullah Ocalan, founder and chairman of the PKK, was captured in Kenya last February by Turkish agents, taken back and sentenced to death for treason by a Turkish court in June.

The sentence is due to be reviewed by the Turkish Court of Appeal in October.

A final decision on execution rests with the Turkish parliament.

Turkey has refused throughout the 15-year war to negotiate with the rebels, whom it considers terrorists. The conflict has killed 37,000 people, most of them Kurds.