The gunmen killed two policemen as they took the corpse from the morgue in the town of Ensenada, about 110 km south of the US border near San Diego, Calif.

"This is unprecedentedf and shows us how far these (drug) organisations can go, " said a police spokesman in the border city of Tijuana.

The dead man was thought by police to be a member of the Arellano Felix drug cartel. His fellow traffickers were believed to have wanted his body to take it away for burial without having to identify themselves when claiming the corpse.

He died earlier this week in a helicopter crash along with another suspected trafficker, but the gunmen failed to get the second man's body from the morgue.

The pair were watching a car race through the desert from the helicopter when it hit electricity lines and crashed to the ground.

Images of the accident were shown on television.

Around 2,350 people have been killed in Mexico this year in drug violence, most of it between rival cartels.

President Felipe Calderon has sent some 25,000 troops to fight the cartels since taking office last December, and Mexico's security forces have made several major cocaine seizures.