A Kurdish party leader says rebels have started to move out of Turkey to bases in northern Iraq, a key stage in the peace process with the Turkish government.

The Kurdistan Workers Party, or PKK, declared a cease-fire in March and agreed to a gradual retreat from Turkish territory as part of peace efforts aimed at ending a nearly three-decade-old conflict that has killed tens of thousands of people.

Gultan Kisinak, the chairwoman of Turkey's pro-Kurdish party, told The Associated Press that a first group of fighters started to move toward the border with Iraq on Wednesday.

The PKK is believed to have between 1,500 and 2,000 fighters inside Turkey. The full withdrawal of forces is expected to take several months.