Mexico City, Jul 9 (IANS): Twenty people were killed and five others were injured when gunmen opened fire in a bar in northeastern Mexico, Xinhua reported.

The attack took place Friday at El Sabino Gordo bar in downtown Monterrey city, the capital of Nuevo Leon state, which is plagued by drug-related violence.

Nuevo Leon and neighbouring Tamaulipas state have been rocked by a wave of violence unleashed by drug traffickers battling for control of smuggling routes into the United States.

A total of 15,270 people died in drug-related violence in Mexico last year, and more than 35,000 people have died since President Felipe Calderon declared war on the country's cartels shortly after taking office in December 2006.

Calderon has deployed tens of thousands of soldiers and Federal Police officers across the country to combat drug cartels and other criminal organizations. The anti-drug operation, however, has failed to put a dent in the violence due, according to experts, to drug cartels' ability to buy off the police and even high-ranking officials.