At least 12 people were killed on Wednesday during clashes between troops and armed drug gangsters in the northern Mexican state of Sinaloa, an official source said.

The State Attorney General's Office said in a statement that the incident occurred Wednesday morning in the town of Guasave, where 10 suspected gangsters and two soldiers were killed.

The military said the gunmen ambushed an army patrol using grenades, automatic weapons and an armored vehicle. Federal, state and municipal police reinforced the military operation and repelled the assailants.

This is the second clash between soldiers and gangsters in a week in Sinaloa. Last Saturday, 15 people died in the town of Choix, including 13 gunmen, a soldier and a policeman.

The clashes came just hours after Governor Mario Lopez announced a tougher strategy to combat organized crime groups.

"An operation is under way to ensure that calm and security return to the Guasave area," he said, denying that the authorities were losing control of security in the state.

Violence has been escalating in the northwestern state, which is dominated by the Sinaloa cartel, the country's most powerful drug gang, led by Mexico's most wanted fugitive, Joaquin "El Chapo" Guzman.

Mexico is plagued by drug-related violence between rival drug cartels and government troops, which has left more than 50,000 dead since President Felipe Calderon launched a "war against organized crimes" in 2006.