More than 20 bodies dumped in Mexico's second city

Suspected drug gang hitmen murdered more than 20 people and dumped their bodies in the centre of Mexico's second city of Guadalajara on Thursday.

Local media reported the bodies were found in several vans abandoned around the western city's iconic Millennium Arches monument, together with a message from drug cartels. The state attorney-general's office said there could be up to 23 dead.

Guadalajara is the capital of the state of Jalisco, home to mariachi music and tequila, and was long spared the beheadings and drive-by shootings that have marked Mexico's war against drugs in other regions.

Known as a stronghold of the Sinaloa cartel, headed by Mexico's most-wanted trafficker Joaquin "Shorty" Guzman, Guadalajara saw a spike in killings as other gangs, including the Zetas, started to contest their dominance of the region.

Local media said the message found with the bodies, dumped less than 1 mile (1 km) from the exhibition hall where the Guadalajara International Book Fair will be held from Saturday, purported to be from the Zetas and was directed at Guzman.

Officials had blamed a surge of killings in the eastern port city of Veracruz in September and October, seen as a warning to the Zetas, on a group with ties to Guzman.

The discovery of the bodies follows the dumping of 16 charred corpses in the Sinaloan capital Culiacan on Wednesday.

Among the Culiacan dead were at least seven people, three of them police officers, who had been kidnapped from a small Sinaloan town on Monday, a local official said on Thursday.

Mexican President Felipe Calderon has deployed the army to crack down on powerful criminal gangs and some 45,000 people have died in the conflict since he took office.

Guadalajara, home to 4.5 million people, hosted athletes from 42 countries last month for the Pan American Games, which were not marred by security incidents. About 600,000 visitors are expected for the city's book fair, organizers said.

The U.S. consulate in Guadalajara warned on Feb. 3 of "a marked escalation of criminal activity". It banned U.S. government officials from traveling after dark between the city and its main airport and urged U.S. visitors to follow suit.

Drugs violence has already engulfed the northern business hub of Monterrey, a city of similar size to Guadalajara, prompting some companies to freeze investment.