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The dumping of 35 seminude, tortured bodies in broad daylight seems to be a  challenge to the violent Zetas cartel.

A gang known to be aligned with Mexico's most-wanted drug lord appears to be making a violent challenge to the dominant Zetas Cartel in the Gulf state of Veracruz, dumping 35 bodies on a busy avenue in front of horrified motorists near where the nation's top prosecutors were about to start a convention.

The cartel known as the New Generation unloaded the bound bodies during rush hour Tuesday as part of a several-month campaign to take the strategic port of Veracruz now controlled by the Zetas drug gang, an official in the Mexican armed forces told The Associated Press on Wednesday.

All 35 victims, who included 12 women and two minors, were linked to the Zetas cartel, said the official, who couldn't be quoted by name for security reasons.

It was the first official acknowledgment of who may have carried out the attack after a banner left at the scene threatened the Zetas and bore the initials "G.N."

A U.S. law enforcement official said the New Generation is believed to be linked to Joaquin "El Chapo" Guzman, widely considered the world's wealthiest drug trafficker.

But the U.S. official, who also could not be quoted by name for security reasons, said it would be surprising to see heavy involvement in Veracruz by Guzman or his Sinaloa cartel, which is based in the Pacific coast state of the same name on the other side of Mexico.

"We don't have anything that corroborates or disputes" that the body dumping was linked to Guzman, the U.S. official said, adding that other sources say the Gulf Cartel could have been responsible. "Sometimes these criminal groups blame the other guys."

Drug trafficking in Veracruz was long controlled by the Gulf Cartel. But the business has been taken over by the Zetas, who had acted as enforcers for the Gulf Cartel before breaking away in early 2010 and waging a bloody war with their former allies across northeastern Mexico.

The Zetas presence in Veracruz has grown since the government launched a crackdown late last year in their main base of Tamaulipas, a border state to the north.

But the gang has also been hit hard in Veracruz by Mexican army and navy operations, leaving them weakened and vulnerable to challenges from rival gangs, the Mexican military official said.

This Gulf coast city is Mexico's busiest port for commercial goods.

The official said there is no way to inspect all the containers coming in. He said many of the drug smuggled in come from Central American, an area where the Zetas have been expanding.

The state is also a main transit route for cocaine and migrants coming from the Guatemalan border.

The Zetas have controlled the corridor, the Mexican official said.

A banner left with the bodies Tuesday criticized the Zetas for killing innocents and charging extortion, warning: "No more." The Mexican officical said the New Generation gang has been carrying out what it calls "surgical" attacks that target Zetas only and no civilians.

Security expert Raul Benitez agreed that the attack could be the work of a gang aligned with Guzman, who is forming alliances to attack the Zetas in other parts of Mexico.

He said Guzman is seeking both to control territory and to punish the Zetas for attacking civilians, something that is shunned by most drug traffickers and that has ramped up government heat on all cartels.

The Zetas have been blamed in two of Mexico's biggest mass killings of civilians since the federal government stepped up a crackdown on organized crime in 2006: the massacre last year of 72 migrants in Tamaulipas and a casino fire last month in the northern industrial city of Monterrey that killed 52 people, mostly women playing bingo and slot machines.

"El Chapo wants to ruin the Zetas in all locations because of their errors in Tamaulipas and Monterrey," said Benitez, of the National Autonomous University of Mexico. "Those were mistakes for other cartels, too."

Photographs of the bodies showed them handcuffed, bloodied and bruised, some marked with a "Z" on their torsos. Veracruz State Attorney General Reynaldo Escobar Perez told MVS radio Wednesday that they had been dead only a few hours.

Escobar, who earlier reported that many of the victims had links to organized crime, said they had records for kidnapping, extortion, murder and drug dealing.

He called the killings unprecedented in a state where crime has been escalating dramatically, including deadly attacks on soldiers and journalists.

"The killing of 35 people is deplorable, but it's even more deplorable the same victims chose to extort, kidnap and kill," Veracruz Gov. Javier Duarte wrote via Twitter.

Authorities said they were examining surveillance video for clues to who left the 35 bodies beneath an overpass while other gunmen pointed weapons at frightened drivers.

Stunned motorists grabbed cellphones and sent Twitter messages warning others to avoid the area, which was alongside the biggest shopping mall in Boca del Rio, part of the metropolitan area of Veracruz city and less than a mile (1 kilometer) from where Mexico's top state and federal prosecutors and judiciary officials began a meeting Wednesday.

The bodies were left piled in two trucks and on the ground near the statue of the Voladores de Papantla, ritual dancers from Veracruz state.

Among the bodies was a local police officer who had disappeared two weeks ago, Escobar told W Radio in Mexico City.

Drug violence has claimed more than 35,000 lives across Mexico since 2006, according to government figures. Others put the number at more than 40,000.

The Gulf Cartel and the Zetas broke apart over the killing of a Zeta in the border city of Reynosa, across from McAllen, Texas, in January 2010.

They have made a war zone of northeastern Mexico, drawing heavy presence of military and federal police in a special operation to stop the violence.

Since then, Zetas from the Mexico border area have been showing up in Veracruz, the U.S. official said.

On Wednesday, soldiers clashed with gunmen in the northeastern border state of Nuevo Leon, killing five, authorities said. Troops were on patrol in the town of Cienega de Flores when they came across gunmen traveling in an SUV, a state police investigator said, speaking on condition of anonymity because he wasn't authorized to talk about the case.

Under Guzman, Sinaloa has grown bloodier and more powerful, controlling cocaine trafficking on the Mexican border with California, while expanding eastward to the corridor between Sonora and Arizona and waging a fierce battle for Chihuahua state bordering Texas.

Mexico's most powerful drug cartel also appears to be expanding methamphetamine production on a huge scale, but has not been known to operate along the Gulf of Mexico coast.

Based on reporting by The Associated Press.

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