Nine bodies have been found in a mass grave in Uruapan, in the western Mexican state of Michoacan.
The bodies were found after an anonymous tip-off to police
A state official said the bodies were found buried with their feet and hands tied and their mouths covered with tape in a warehouse in the city.
President Felipe Calderon sent 7,000 soldiers to Michoacan state last month in an attempt to curb drug violence.
Drugs gangs have been blamed for more than 2,000 murders in Mexico last year, including some 500 in Michoacan state.
The bodies, of eight men and one woman, were found after police received an anonymous tip-off.
All nine bodies were in advanced stages of decay and only one has been identified.
President Calderon, who was sworn in last month, has vowed to curb drug-related violence.
More than 50 people have been arrested in Michoacan since thousands of federal troops were deployed there in December.
Michoacan and Tijuana, on the US border in the north, have been the scene of much drugs-related violence recently.
In one incident, masked men burst into a bar in Uruapan and flung five human heads onto a crowded dance floor in an apparent warning to a rival gang.
Mr Calderon has also sent thousands of federal soldiers and police to Tijuana to help fight drug trafficking and gang violence.