Motorbike gunmen Friday shot dead a senior police officer investigating sectarian killings in Quetta, police said.

Police said the assailants sprayed Jamil Kakar with bullets when he left his house in his official car, killing him and injuring a police guard.

"Jamil Kakar died on the spot. We are investigating the motives of the attack," Salim Lahri, another senior police official in Quetta told AFP.

"The attackers fled on the motorcycle, we have launched a search for their arrest."

Officials said Kakar was investigating several sectarian attacks and that he had received threats in the recent past.