Kurdish rebel leaders have confirmed that their fighters will begin withdrawing from Turkey into bases in neighbouring Iraq on Wednesday and warned Ankara against "provocations and clashes" which could hamper their retreat.

"Our guerrilla forces will take action for starting the pullout process" on Wednesday, the outlawed Kurdistan Workers' Party (PKK) command said in a statement carried by the pro-Kurdish Firat news agency on Tuesday.

But the statement claimed: "Constant surveillance flights of the unmanned aerial vehicles are delaying the withdrawal process."

The group also alleged that Ankara was building up its military forces at the border with plans for "provocations and clashes".

The Turkish military has not announced any such steps.

A first batch of Kurdish rebels will return to their bases in northern Iraq in a week, according to the PKK, which said: "This process will continue in a planned and organised way."

There are an estimated 2,000 armed PKK militants inside Turkey and up to 5,000 in northern Iraq, which Kurdish rebels have used as a springboard for attacks targeting Turkish security forces in the southeast.

Kurdish rebels announced on April 25 that they would begin withdrawing on May 8 as part of a new peace drive between Ankara and jailed Kurdish leader Abdullah Ocalan.

It followed a landmark ceasefire call in March by Ocalan, who has been involved in months of clandestine peace negotiations with Turkish security services.

Turkish Prime Minister Recep Tayyip Erdogan suggested Tuesday that the rebels' main priority should be to lay down their weapons.

Erdogan's Islamist-rooted government has faced harsh criticism from opposition parties over the negotiations, accusing Ankara of a lack of transparency.

The PKK, blacklisted as a terrorist group by Turkey and much of the international community, launched an armed rebellion for self-rule in the Kurdish-majority southeast in 1984 which has since claimed around 45,000 lives.

The rebel command also called on independent rights groups to "take part in the process" by observing the pullouts, saying they could contribute to a safe operation.