Mexico holds ex-army Guatemalans

Guatemala has confirmed some of the men had been soldiers

A group of armed Guatemalan men held in Mexico on suspicion of aiding drug gangs had been trained by an elite soldiers' unit, officials say.

At least four in the group of seven men detained had been in the Guatemalan army, Mexico's attorney general said.

Mexican authorities are investigating whether the heavily-armed group had entered the country to fight alongside a local gang of drug smugglers.

Mexico is battling a surge in violence blamed on competing drug gangs.

The seven men were arrested by Mexican authorities near the Guatemalan border on 10 September.

They were carrying six machine-guns and hundreds of rounds of ammunition and are likely to face charges of weapons smuggling.

Drugs link

Guatemalan officials confirmed on Thursday that four of the men had been trained by the country's Kaibiles special forces unit, which specialises in jungle warfare.

Drug wars hit Mexican town

Human rights groups accuse the Kaibiles of carrying out massacres during Guatemala's civil war.

"These people took a 40-day course [with] the Kaibiles," Mexican Attorney General Daniel Cabeza de Vaca told the Associated Press news agency.

"We are still not certain whether they were collaborating... with some organised crime group, we're still investigating that," he said.

Earlier this week, Mexican Defence Minister Clemente Vega Garcia said the Guatemalan men had come to Mexico as part of an alliance with gangsters from the country's Zeta group.

The Zetas are reputedly made up of deserters from Mexican special forces units who now serve as hit-men for the Gulf Cartel, a drug-smuggling gang based in the town of Nuevo Laredo, near the US border.

Nuevo Laredo has been the focus of recent drugs violence in Mexico - most of it linked to a turf war between the Gulf Cartel and another group, the Sinaloa Cartel.