"One of our heroic soldiers was seriously injured in a mortar attack by PKK terrorists on one of our bases. He was taken to hospital where he could not be saved," the Turkish Defence Ministry said in a statement.

"We immediately retaliated and according to first information received, three terrorists were neutralised," the statement added, stating that the attack had occurred in an area close to the Turkish border.

Turkish forces frequently conduct operations against PKK rear bases in northern Iraq.

Turkey launched an offensive in April -- by air and sometimes land -- targeting Iraq rear-bases of the PKK, which it considers a "terrorist" organisation.

The PKK's pan-Kurdish agenda -- for a homeland straddling Syria, Turkey, Iraq and Iran -- has often put it at odds with Iraq's autonomous Kurdish government, which has sought to maintain good relations with Ankara.

Turkish troops have maintained a network of bases in neighbouring northern Iraq since the mid-1990s on the basis of security agreements struck with Saddam Hussein's regime.

The PKK has waged a rebellion in the mainly Kurdish southeast of Turkey since 1984 that has claimed more than 40,000 lives.