Mexican police have found 12 decapitated bodies in Southern Mexico, as violence rises in Yucatan peninsula, a tourist resort.

Eleven headless bodies with signs of torture were dumped in a field on Merida city's outskirts. A 12th body was found about 80 kilometers (50 miles) away.

Police claim all men were decapitated alive, although the heads of the victims have not yet been found as yet.

The victims were branded with the letter Z suggesting the notorious Zeta hit squad may have been behind the murders.

The Zetas, one of Mexico's most powerful drug trafficking gangs, are the highest-profile rivals to Joaquin Guzman, a powerful drug lord who escaped from a high-security jail in a laundry van in 2001.

Indeed, the brutal style of execution bears all the trademark signs of Mexico's escalating drug war.

Over the past four years, the rival cartels have fought each other for control of trafficking routes, local production and growing domestic markets.

President Felipe Calderon launched a nationwide battle to take back territory controlled by some of the world's most powerful drug gangs in 2006.

Mexicans will take to the streets on Saturday in nationwide protests at the escalating violence, which has seen decapitated bodies littering southern and northern Mexico.

More than 2,700 people have been killed in Mexico so far this year while kidnapping rates have exceeded those of Colombia and Iraq.

HSH/RA