MEXICO CITY Aug 20 (Reuters) - At least three people were killed by an ammonia gas leak from a pipeline owned by state oil monopoly Pemex in southern Mexico on Tuesday and 1,500 people were evacuated from the area and taken to shelters, the company said.
Mexican media put the death toll at four and said some 40 others were poisoned by the leak in the southern state of Oaxaca.
Pemex said the leak was caused when the pipeline was damaged by heavy machinery operated by a private company doing road work.
Pemex has had a poor safety record in recent years.
Nearly 40 people were killed in January in a massive explosion at Pemex's Mexico City headquarters. Investigators said the blast was caused by a buildup of methane and other gases that had collected for years in the basement of the building with no ventilation.
Mexican President Enrique Pena Nieto has proposed an overhaul of the energy sector to attract private investment to help stem a slide in oil output over nearly a decade and drag the giant Pemex into the modern era.