Turkish officials say unknown assailants have fired on a pro-Kurdish party's campaign vehicle, killing the driver — the latest violence against politicians or political parties ahead of Sunday's general election.

The governor's office for Bingol province said the 35-year-old driver was found shot dead near the hired minibus of the People's Democratic Party, or HDP, late Wednesday.

The attack comes weeks after bomb explosions at HDP offices injured six people in southern Adana city and neighboring Mersin.

The motive of the attack was not known but the party is frequently accused by the ruling party and nationalists of links to Kurdish rebels fighting for autonomy in southeastern Turkey.

Last month, officials said two supporters of a small Islamic party were killed in a fight with Kurdish party supporters.