Nine of the dead were found hanging from a bridge in the northern border city of Nuevo Laredo, a killing spree authorities blamed on drug gang violence.

A Mexican drug cartel claimed responsibility for the murders, a state government official told AFP on condition of anonymity. He did not say which cartel.

Some 40 percent of Mexican exports sent by land to the United States cross through Nuevo Laredo, making the town a choice site for drug smugglers.

"The nine bodies were hanging from a bridge on Colosio Boulevard," over the express lane leading to the highway that links Nuevo Laredo to Monterrey, Mexico's third largest city, the official said.

He said the victims were likely kidnapped from a bar hours earlier.

One of the victims was a "young man, 16 years old," and all the bodies showed evidence of "bullet wounds to the head," the Tamaulipas state prosecutor's office said in a statement.

The office later revealed that seven more bodies of men aged between 50 and 65 had been found on a road near the town of San Fernando. All of them had tied hands and gunshot wounds, a sign of execution-style killings.

The gruesome find was made no far from the site where 72 dead immigrants, allegedly executed by the Zetas drug cartel, were found in 2010.

The chilling display followed Wednesday's arrest of Jorge Eduardo Costilla Sanchez, a senior leader of the Gulf cartel. In early September, authorities arrested Mario Cardenas Guillen, another Gulf cartel leader.

The Gulf cartel and its former allies, the paramilitary Zetas, have been fighting to control the Nuevo Laredo smuggling routes for at least two years. A third gang, the Sinaloa Federation, has also sought to control the routes.

Analysts have predicted a rise in violence as rival gangs try to capitalize on the blows to the Gulf cartel.