Turkish warplanes and artillery have periodically bombed and shelled PKK positions in northern Iraq over several months, helped by US intelligence based in Iraq.
 
In February, the military launched a week-long ground incursion against the PKK by sending thousands of troops into Iraq.
 
Turkish authorities said that 240 fighters were killed in the campaign, along with 27 Turkish soldiers.
 
The cross-border operation prompted concern in Washington about further regional instability and was watched closely in Turkey's financial markets.
 
Turkey blames the PKK for the deaths of nearly 40,000 people, mostly Kurds, since the group began its armed campaign for an ethnic homeland in southeast Turkey in 1984.
 
Turkey, like the European Union and United States, considers the PKK a terrorist organisation.