MEXICO CITY – Several explosions believed to be the work of saboteurs ripped apart natural gas pipelines for Mexico’s state oil monopoly early today, the company said. There were no reports of injuries.

Mexican state oil monopoly Petroleos Mexicanos, or Pemex, issued a statement saying it believed the explosions, which happened about 2 a.m. and forced the evacuation of 12,000 people, were deliberate.

In July, a small, left-wing guerrilla group claimed to have attacked a major Pemex gas pipeline extending from central Mexico City to Guadalajara, the industry-rich capital of the western state of Jalisco.

Those attacks forced at least a dozen major companies, including Honda Motor Co., Kellogg Co. and The Hershey Co., to suspend or scale back operations, and sent the Mexican government scrambling to increase security at “strategic installations” across Mexico.

At the time, the group pledged to continue its attacks against government installations.

Four of the explosions Monday produced fires, which Pemex said were under control.

It was not clear what security measures were in place at the pipelines that exploded today. Except for small businesses prevented from opening by the evacuations, there did not appear to be any major effect on area businesses.

Pemex said at least five pipelines were affected, but said it had no reports of deaths or injuries.