PRESS ASSOCIATION -- At least 17 people have been killed in a bar massacre in the northern Mexico city of Monterrey when riflemen opened fire on the clientele and employees, a state forensic investigator said.

Monterrey, a major industrial hub, has seen a spike of violence since the Gulf and Zeta cartels began fighting for control of drug traffic there two years ago.

The medical examiner's official said his office has recovered 17 bodies, including those of women, from the crime scene. He spoke on the condition of anonymity because he was not authorised to speak on the record.

Police sources would not confirm the number of dead people with and referred reporters to local prosecutors, who are not giving an official account of the shooting.

Federal police spokesman Jose Ramon Salinas said that high-powered weapons used in the shooting indicated it might have been a drug cartel confrontation.

Police sealed off the crime scene, which was still heavily guarded by the Mexican army and federal police by early on Saturday morning.

Other central businesses looked closed earlier than usual after news of the massacre broke.

Mexican media are reporting 20 killed. The newspaper Reforma reported five more were wounded.