Police launched a manhunt Thursday for a gunman who shot and killed a Saudi Arabian diplomat, but they were unable to determine whether the motive for the killing was personal or political, a senior police official said.

"We believe the gunman is still in Bangkok and will do our best to get him as soon as possible," said Pol. Lt. Gen Pravit Wongviseth.Pravit told reporters the motive for the murder might be international political conflict or a personal grudge arising from the victim's embassy duties in issuing visas for workers entering Saudi Arabia.