ISTANBUL (AFP) - Gunmen opened fire on a pro-Kurdish People's Democratic Party (HDP) campaign bus in southeastern Turkey on Wednesday, killing one person just days before parliamentary elections.

The victim, identified as the driver of the bus, was found dead with gunshot wounds to the head near the vehicle in the Karliova district of Kurdish-majority Bingol province, news agency Dogan reported.

A large-scale search operation was underway throughout the area to find the unidentified assailants, who fled the scene, Dogan said.

The campaign leading up to the June 7 parliamentary vote has been marred with violence, mostly targeting the HDP.

In May, two blasts targeting the party's headquarters in the southern cities of Adana and Mersin injured several people.

Should the HDP pass the 10-per cent threshold needed to have MPs in parliament, it would become more difficult for President Recep Tayyip Erdogan to reach his goal of changing the constitution to boost presidential powers.