The recovery work was called off at nightfall and was to resume early Wednesday, he added, raising the prospect of more bodies. Three mass graves have been found in Mexico in the last year, each full of bodies dumped by drug cartel gunmen.

Two were in Guerrero, with 55 bodies found in June in Taxco and 18 in November near the beach resort of Acapulco. The third was found in Nuevo Leon state, in the north, containing 51 bodies.

The government has lauded recent arrests and killings of a string of drug gang leaders as signs of success in a military crackdown President Felipe Calderon launched against organized crime in 2006. More than 34,600 people have died in battles involving rival cartels and security forces since the operation began.