MONTERREY, Mexico, Nov 9 (Reuters) - Mexican naval officers fought a ferocious gun battle with suspected drug hitmen outside a shopping center in the northern port city of Tampico on Friday, witnesses and Mexican media said.

Officers fought around a dozen armed men after being shot at from two SUVs during a routine patrol of the city center on Mexico's Gulf coast on Friday, witnesses told Reuters.

The suspects fled on foot and the army closed off part of the city to find them, Reforma newspaper said.

"I saw about 200 bullet casings on the street, a grenade (unexploded) and blood stains," local journalist Lorenzo Martinez told Reuters.

Mexican authorities declined to comment on the gun battle in Tampico, in the state of Tamaulipas. Mexican cities in Tamaulipas bordering Texas are dominated by the powerful Gulf drug cartel and its armed wing, the Zetas.

Mexican President Felipe Calderon has sent thousands of troops to Mexico's border cities this year to try to stop the drug violence.

Last month, authorities seized more than 11 tonnes of cocaine in Tampico, one of Mexico's biggest ever drug busts.

Around 2,350 people have been killed in Mexico this year in drug violence, most of it between rival drug gangs. (Reporting by Robin Emmott in Monterrey and Magdiel Hernandez in Reynosa, editing by Todd Eastham)

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