Soldiers in Mexico have uncovered a mass grave with at least 18 bodies in the northern state of Nuevo Leon

Security forces said an anonymous tip-off led them to the site almost the size of a football pitch. Investigators believe drug gangs used the remote spot to torture and execute their victims. Recently, two more such graves have been discovered in Nuevo Leon, which is at the center of a violent battle between rival drug gangs. The bodies were found in a pit east of the city of Monterrey. Crime scene investigators are using diggers to search for more bodies. They said they had found two more spots inside the pit where the earth had been disturbed and where they believed more bodies could be buried. Investigators said the layout of the site, with large amounts of blood found along an earthen ramp and traces of gasoline found at the bottom, suggested the victims were led half-way along the pit, where they were tortured and killed. Their bodies were then dumped a further 10 meters along the pit, where they were set alight. More than 200 people have disappeared in the border state in recent years. Nuevo Leon has seen an increase in violence which police say stems from a deadly fight between the Gulf cartel and their former gang of hit-men, the Zetas, for control over lucrative drug routes.