Kurdistan Workers ' Party(PKK) militants have abducted four Turkish soldiers in Turkey ' s southeastern province of Diyarbakir.

The soldiers were on patrol in the province when they went missing on Sunday.

A military source said that operation to locate them is underway.

The reason behind the abduction is still unknown, but tensions have been high in the region after two protesters were killed on Friday during confrontation with police in the town of Yuksekova in Hakkari province.

The two Kurds, aged 34 and 32, died in skirmishes triggered by claims that PKK members’ graves had been destroyed.

On Saturday, Turkish police forces clashed with people attending the funeral of the two protesters in Yuksekova.

The demonstrators burned tires on a road in the city and pelted the forces with stones during a protest, which was held on the sidelines of the funeral.

Also on Sunday, clashes erupted between police and demonstrators in the town of Diyarbakir.

Police used tear gas and water cannons to break up a protest by around 5,000 demonstrators. At least five demonstrators were arrested during the clashes.

Almost a dozen people, including four police officers, were also injured.

Meanwhile, pro - Kurdish Peace and Democracy Party(BDP) demanded that Turkish Prime Minister Recep Tayyip Erdogan apologize for the deaths.

“We wonder whether Erdogan will say anything about those two people who died in clashes, as the Hakkari governor’s office did. Will he apologize to our people for the killing of those two workers? That’s what we want to hear, ” said Selahattin Demirtas, the co - chairman of the BDP, who attended the funeral in Hakkari.

The PKK has been fighting for an autonomous Kurdish region in southeastern Turkey since the 1980s. The conflict has killed more than 40,000 people.