Police are investigating whether separatists are responsible for the fatal shooting Monday of a policeman who was guarding a gas station in the restive Indonesian province of Papua, a report said.

Four gunmen shot Sgt. Sharul, who used only one name, and stole his gun in the town of Mulia near the Freeport gold and copper mine, the Antara news agency quoted Puncak Jaya district police Chief Aleks Korwa as saying.

Police are investigating whether the gunmen were activists seeking independence for Indonesia's easternmost province, Korwa said.

Papua police spokesman Col. Agus Rianto could not be immediately contacted for comment.

Last month, gunmen ambushed a convoy of vehicles from the mine, wounding at least seven people, including four police officers and an American.

It was the latest in a string of ambushes on the road linking the mine with the town of Timika that have claimed eight lives since July 2009, including an Australian technician.

The mine, run by a subsidiary of Freeport-McMoRan Copper & Gold Inc. based in Phoenix, Arizona, has been repeatedly targeted with arson, roadside bombs and blockades since production began in the impoverished province in the 1970s.

The region is the scene of a low-level insurgency and police routinely guard businesses such as gas stations.