The victims, all male, were discovered at dawn near a shopping mall along with threatening hand-written messages that are typically left as a calling card by drug cartels, authorities said.

At least a dozen more bodies were found at several scenes of violence around the city early on Saturday, local media reported in more examples of drug gang skirmishes.

The messages found near the headless bodies were signed by Mexico's most wanted man, Joaquin "Shorty" Guzman, the leader of the powerful Sinaloa cartel that is fighting rivals over the area, police added.

The half-naked bodies were mutilated and badly beaten, and machetes appeared to have been used, police said.

Acapulco is a bustling metropolis with beaches and a nightlife 250 miles from the Mexican capital.

The Sinaloa gang is waging a brutal war for control of the city, its port and routes toward the United States, fighting the weakened Beltran Leyva cartel and the South Pacific cartel, a breakaway faction of the Beltran Leyva gang.

The gangs are spreading fear in Acapulco, damaging the vital tourism industry, although business owners are desperate to assure visitors their city is safe for tourists.

A burned-out truck and four other destroyed vehicles were found near the bodies on Saturday. Four other murder victims were found in other parts of the city in separate incidents, including a police chief, local media reported.

Drug violence has killed more than 30,000 people since President Felipe Calderon launched his army-led crackdown on drug cartels in December 2006.