The Mexican Navy is searching for one of its helicopters that disappeared four days ago over an area where drug cartels are active.

墨西哥海军正在搜寻四天前失踪的一架直升机，该直升机是在贩毒团伙活跃的地区失踪。

The navy said air traffic controllers had lost contact with the helicopter, with four crew on board, as it was travelling over Michoacan state.

Michoacoan is the stronghold of the Knights¹ Templar drug gang.

There have been 28 attacks on helicopters since the government declared war on the cartels in 2005.

The navy said the Panther helicopter had taken off from Manzanillo on the Pacific Coast on Friday, and lost contact 35 minutes later.

Mexico's President Felipe Calderon deployed² the military six years ago to help fight Mexico's drug gangs.

The navy has since become a target for the country's powerful drug cartels, which are often better armed than the security forces.