(AFP) - Investigators recovered 18 bodies from a mass grave near the Mexican beach resort city of Acapulco, police said Wednesday, adding that more bodies could be buried there.

Eighteen bodies had been found when digging stopped Wednesday evening in a rural area near Acapulco -- about 235 miles (378 km) south of Mexico City -- said Guerrero state police chief Fernando Monreal.

The discovery came amid a spike in suspected drug gang violence in the area.

News reports suggested the grave could contain the bodies of 20 missing men from the neighboring state of Michoacan who were allegedly abducted by armed men on September 30. Monreal said the bodies had not yet been identified.

Police began digging at the site after receiving an anonymous tip which led them to discover two bodies nearby Tuesday.

More than 30 people have died in separate violent attacks in Acapulco the past 10 days, while a Canadian businessman disappeared there and is feared dead after his rental car was found with a burned body, which is yet to be identified, in the trunk.

An eruption of suspected drug violence has left more than 28,000 people dead nationwide since the launch of a military clampdown on organized crime in 2006.