ACAPULCO, México(Reuters) - The bodies of eight men were found in a van along the highway that connects Acapulco with Mexico City, in one of the latest violent episodes to shake the southern Mexican state of Guerrero, a government official said on Monday.

The bodies were discovered close to midnight on Sunday, wrapped in plastic bags and secured with plastic tape.

Roberto Alvarez, spokesman for Coordination Guerrero, which coordinates state and federal law enforcement, said in a video announcement sent to reporters that the men were aged 25 to 35 and died from suffocation. The bodies showed evidence of torture, he added.

Two had their faces exposed, and six were covered with sheets, according to police sources who were not authorized to speak publicly about the matter.

In Guerrero, different criminal groups tied to the poppy trade wage bloody turf wars while the army destroys crops.

Poppies produce opium, a critical ingredient in heroin.

In September of 2014, 43 students went missing in one of the most notorious cases of forced disappearances in Mexico. Municipal, state and federal police were found to be involved. Only a fraction of the remains of one of the students has been identified.