Mexico City - Mexican police found five human heads Tuesday in portable coolers on a road in Ixtlahuacan del Rio, some 600 kilometres northwest of Mexico City.

On the inside of the coolers' lids, two messages had been written in black ink, with threats addressed to someone that was only identified as "Goyo," a spokesman for the public prosecutor's office in the state of Jalisco told Deutsche Presse-Agentur dpa.

The authorities said the heads of the five men had been severed just hours before they were found.

Police were combing the rural area where the heads were found, some 40 kilometres northwest of the city of Guadalajara, in search of the bodies.

Some 6,300 people were killed last year in Mexico in incidents that the authorities link to organized crime and drug gangs. Since January, over 1,000 have been killed in similar circumstances. (dpa)