An object found in a suspicious-looking vehicle parked on the roadside in the border city of Agua Prieta, Sonora, has been likened to a bazooka.
But the three-meter-long tube in the back of a panel van is believed to have been used to launch drugs rather than rockets.
Federal agents seized the vehicle after it was found abandoned without license plates and with the doors left open.
Inside was the metal tube, an air compressor, a gasoline engine and an air storage tank. Police believe it was a form of cannon, intended to launch packages of drugs over the Mexico-U.S. border.
A hole had been cut in the back of the van into which the tube would be placed in readiness for firing.
U.S. authorities say such cannons have been in use by drug traffickers since 2012, launching cans or packages containing marijuana, crystal meth and cocaine, which have been found on the U.S. side of the border.
The cannons have had a range of at least 200 meters.
The van itself had been reported stolen in Hermosillo in July.
Source: Reforma (sp)