Four Turkish police officers killed in bomb attack

The blast is the latest in a succession of frequent attacks against security forces by Kurdistan Workers' Party

DIYARBAKIR, TURKEY: Four Turkish police officers traveling in a vehicle in southeast Turkey were killed on Thursday when explosives believed to have been planted by Kurdish militants were detonated as they passed by, security sources told Reuters.

The blast in Mardin province is the latest in a succession of frequent attacks against security forces by Kurdistan Workers' Party (PKK) militants since a two-year-old ceasefire ended in July, leaving a peace process in tatters.

No further details were immediately available.

Turkish warplanes bombed PKK positions on Wednesday after one soldier was killed in the same region. State media said 20 militants were killed in those air strikes.

More than 70 members of Turkey's security forces have been killed since the PKK attacks began. State-run Anadolu Agency says more than 900 PKK militants have been killed in that period in southeast Turkey and Iraq, where the PKK has bases.

The PKK, designated a terrorist organisation by Turkey, the United States and European Union, took up arms in 1984, and more than 40,000 people have since been killed.

The violence halted after Ankara began talks with the group's jailed leader, Abdullah Ocalan, in 2012.