Gunmen kidnapped nine police officers investigating a death in the southern Mexican state of Guerrero, and the bodies of two of the officers were found later.

Fernando Monreal Leyva, director of the State Investigative Police, said one of his agency's commanders and a team of eight agents had gone to identify and recover a body in a northern part of the state on Friday. He said contact was lost with the group that afternoon, and officials learned the officers had been seized by an unknown gang of gunmen.

Searchers found the bodies of two officers near El Revelado, the community where the police group was kidnapped, Mr Monreal said, adding that the Mexican army was helping police search for the other missing officers.

Several drug gangs are battling for control of smuggling routes in Guerrero state.

In another part of Guerrero, unidentified men travelling in two vehicles threw two human heads into a refreshment stand in Coyuca de Catalan, state police said. One of the heads was blindfolded with duct tape.

Mr Monreal said the incident was not connected to the kidnapping of his officers.

Authorities in Ciudad Juarez, a northern border city gripped by drug violence, said police arrested two alleged leaders of the Aztecs gang linked to at least 10 murders, including the killing of a federal police officer last month.

The detainees were identified as Gonzalo Dominguez Sanchez, known as "El Chore," and Eduardo Rocha, alias "El Dienton," both 29. Federal police said Dominguez was the successor to alleged Aztecs leader Jesus Ernesto Chavez Castillo, "El Camello," who was arrested on July 2. Rocha was described as the gang's second in command.

Federal police said the men were caught with an AR-15 rifle, two loaded pistols and more than 1.6 kilograms of cocaine.

Across Mexico, drug-gang violence has claimed more than 28,000 lives since December 2006, when President Felipe Calderon took office and deployed thousands of troops and federal police to crack down on the cartels.