Authorities in the Caribbean resort of Cancun were working on Monday to identify six bodies found in a cave over the weekend.

The investigation comes as authorities in the state of Guerrero announced that at least 55 bodies had been recovered from an abandoned silver mine that became a dumping ground for apparent victims of Mexico's drug violence.

The search for more victims ended over the weekend at the mine on the outskirts of Taxco, attorney general for the state of Guerrero.

He said the overall toll could still rise, however, as forensic examiners try to determine whether other human remains, clothing and shoes found in the nearly 500-foot-deep (150-metre-deep) shaft correspond to the bodies already found.

Among the dead was a recently kidnapped prison director, although the majority of victims of have not been identified.

At least 15 people have been detained over the case, which officials suspect is tied to drug gang violence.

The nearly 500-foot (150-metre) deep mine is located on the outskirts of Taxco, which is popular with tourists and is best known for its silver jewelry.

Authorities were tipped off about the mass grave in late May after they arrested an organised crime suspect in the nearby city of Iguala.

Meanwhile, Quintana Roo State Attorney General Francisco Alor said the victims found in the cave in Cancun included "four male bodies and two female bodies."

Toxicology results found drugs in all six victims.

Alor initially said that three of the bodies were cut open and their hearts removed, but autopsy results released on Monday showed otherwise.

The hearts were destroyed through multiple stabbings but were never removed, Alor said.

Three of the bodies had the letter 'Z' carved on their abdomens, a possible reference to the Zeta drug gang.

The discovery comes days after the mayor of Cancun was charged with drug trafficking ties and accused of protecting two of Mexico's most brutal drug gangs.

Gregorio Sanchez has since been barred from politics, ending his run for governor of the state of Quintana Roo.

Other drug violence also was also reported across Mexico on Monday.

In Cuernavaca, in the central state of Morelos, police reported the discovery of three victims with their heads decapitated.

A note left at the scene threatened people with ties to alleged drug trafficker Edgar Valdez Villareal, who authorities say is fighting Hector Beltran Leyva for control of the Beltran Leyva cartel.

Drug gang violence has claimed more than 22,700 lives since President Felipe Calderon launched a crackdown on cartels shortly after office in late 2006.