MEXICO CITY (Reuters) - Mexican authorities on Friday blamed a surge of killings in Veracruz on a group linked to Mexico's most powerful drug lord, Joaquin "Shorty" Guzman, who has been fighting a turf war with rivals in the port city.

Navy spokesman Jose Luis Vergara said 32 bodies found on Thursday in Veracruz and another 35 dumped there on September 20 were the work of the "Jalisco New Generation" cartel (CJNG), a group with close ties to Guzman's Sinaloa cartel.

A group called the "Zeta Killers" claimed responsibility for the deaths, but Vergara said the name was created by the CJNG to threaten one of Mexico's most notorious and brutal drug gangs, the Zetas. Authorities have been eager to dispel the idea that independent vigilantes have formed paramilitary groups to target drug trafficking gangs.

"It must be underlined they are another organized crime group hostile to ... the Zetas, a cartel with whom they are fighting for control over activities and illegal funds in Veracruz," Vergara said in a televised statement.

"No criminal acts or propaganda will make the state withdraw," he added.

The 32 corpses were found just two days after the Mexican government unveiled a plan to bolster security in Veracruz state, of which the port of the same name is the biggest city.

Founded by army special forces deserters, the Zetas were once an elite group concentrated in northern Mexico who acted as the armed wing of the Gulf Cartel.

But since splitting with their former bosses early last year, they have extended operations, sparking conflict with established cartels for control of smuggling routes.

Veracruz is one of Mexico's busiest ports, where the Zetas and Guzman are now battling for primacy.

Guzman is Mexico's most wanted man and runs an empire of methamphetamine, marijuana and cocaine smuggling that has earned him a spot on Forbes magazine's list of billionaires.

Alberto Islas of consultancy Risk Evaluation said it was too early to say what lay behind the Veracruz killings.

But he said the CJNG were allies of Guzman, having been founded by associates of his former lieutenant Ignacio "Nacho" Coronel, who died in a firefight with soldiers last year.

Since Calderon launched his crackdown on cartels at the end of 2006, the drugs war has cost more than 44,000 lives, damaging his party's chances of re-election next year.

But he remains defiant on the need to tackle the gangs.

"Fighting crime is not optional. It's a categorical imperative," he said in a speech on Thursday.

(Reporting by Dave Graham; editing by Anthony Boadle)