MEXICO CITY -- Between 20 and 25 bodies were recovered from an abandoned silver mine in southern Mexico, apparently victims of drug gang violence, federal police commissioner Facundo Rosas said Sunday.

The corpses appear to have accumulated over an undetermined time as they were tossed over a 300-foot precipice into the abandoned mine, located near Taxco, a colonial-era city popular with international tourists. The region is dotted by hundreds of mines.

Rosas said authorities were alerted to the mass grave by a suspect and they began pulling bodies from the mine late Saturday and continued their work Sunday. He didn't give the identities or causes of death of the victims.

Police and military crews exploring the underground site wore breathing equipment to guard against the possible noxious gases in the mine.

The state of Guerrero, where Taxco is located, is plagued by drug violence among rival gangs, and marked by brazen attacks on police and soldiers engaged in a crackdown on traffickers.

But Taxco is better known for its silver jewelry, winding streets and Holy Week processions.

Rosas said Sunday that in an unrelated case, authorities arrested two brothers named on Mexico's Most Wanted list for their ties to organized crime.

The brothers are suspected members of La Linea drug gang, and Rosas said they're tied to drug dealing, kidnapping, extortion, car theft and several murders in the north Mexico state of Chihuahua.

Meanwhile in the state of Morelos, south of Mexico City, police identified human remains left on a road in several different plastic bags as a local prison director.

The state prosecutor said in a written statement that the director had headed the prison for two months. The statement did not mention a motive for the murder.

More than 23,000 people have been murdered in drug gang violence since President Felipe Calderon cracked down on drug traffickers in late 2006.