The state prosecutor in Michoacan said that nine bodies, hands bound and shot, were found on an abandoned property near the town of Buenavista Tomatlan along with a sign indicating they may have been members of the Knights Templar cartel.
The remote area near the Jalisco state border has suffered a wave of violence for most of this year, as self-defence groups have risen up to battle the Knights Templar, which controls the territory with killings and extortion.
The sign read: "For those who continue to support the Knights Templar, we are here, united," said prosecutor's spokesman Alejandro Arellano said.
The note was signed with the initials of the New Generation, as well as the initials G.C., indicating a community-based, self-defence group.
The government of President Enrique Pena Nieto sent thousands of troops and federal police to the area in May to regain control of the state. While residents initially cheered the arrival and some self-defence groups agreed to put down their arms, the calm was short-lived.
The government response so far has mirrored that of Pena Nieto's predecessor, Felipe Calderon, who started his drug offencive as president by sending troops to Michoacan in 2006, and periodically thereafter, with little result.
The Knights Templar launched a coordinated attack on federal police in Michoacan last month, killing at least four officers and wounding at least five more.
They also killed one of Mexico's highest-ranking navy officers and a bodyguard last month when they ventured onto a local road in Michoacan to get around highway roadblock.
Authorities in Guerrero yesterday said that they found 14 bodies, eight in San Miguel Totolapan in the Tierra Caliente and six in a mass grave near the colonial tourist town of Taxco.
The state prosecutor's office said in a statement that five in San Miguel Totolapan were found in the back of a Ford pick-up in military-style dress and with heavy arms and munitions, including a grenade.
The statement said three more young men were found shot to death in the same town, but did not specify where.
