Police in the popular Mexican beach resort of Cancun found the bodies of 12 people on Friday, with signs they were tortured and killed by drug gang members.

Police recovered the bodies of nine men and three women from graves in an area less than two miles from Cancun, a tourist destination increasingly drawn into Mexico's drug war, and said more corpses might be found.

"They died of suffocation. They were found with their hands and feet tied and with signs of torture. At least three were cut post-mortem on their chests with the letter Z," said state official Francisco Alor.

The letter Z is a symbol in Mexico of the Zetas drug gang, the former armed wing of the powerful Gulf cartel.

President Felipe Calderon launched a military crackdown on the drug cartels in late 2006, sparking turf wars and attacks. More than 25,000 people have since been killed, many of them beheaded or strung from bridges.