The threat was posted on Facebook group, GM Pheonix.
A post was created using the group’s account, in which a person challenged PM Lee to find him, or he will put a bullet through the Prim Minister’s head.
This post was followed by others which showed a handgun, and a bullet cartridge.
The person who put up the post also said that a person wearing a black hoodie had dropped off a bomb at Changi Airport.
Police are investigating the incident.
GM Pheonix is a Facebook group dedicated to enthusiasts of the first-person shooter game, Blackshot Online.