Amex1
Smoke rises from the explosion site at Mexican national oil company Pemex's Pajaritos petrochemical complex in Coatzacoalcos, Veracruz state, April 20, 2016. Angel Hernandez/Reuters

An explosion rocked a major petrochemical facility of Mexican national oil company Pemex in the Gulf state of Veracruz on Wednesday, killing at least three people and injuring dozens more, senior officials said.

Luis Felipe Puente, head of federal emergency services, told Reuters that three people had died in the blast and as many as 45 were injured. The governor of Veracruz state, Javier Duarte, told local television that more than 60 people were injured.

Pemex said the explosion, which sent a huge, dark plume of smoke billowing into the sky, occurred at the facility's chlorinate 3 plant near the port of Coatzacoalcos, one of the company's top oil export hubs. The cause was unclear.

Local emergency officials said hundreds of people had been evacuated from the site. Television footage showed an initial burst of flames followed by a tower of thick smoke. A Pemex official said local oil exports were not affected by the blast.

The incident took place at Petroquimica Mexicana de Vinilo, or PMV, a vinyl petrochemical plant that is a joint venture between Pemex's petrochemical unit and Mexican plastic pipe maker Mexichem.

The plant, operated by Mexichem, is located within Pemex's larger Pajaritos petrochemical complex.

Mexichem said in a brief statement that the explosion occurred in an ethylene unit at the plant. The company could not be immediately reached for further comment.

In February, a worker was killed in a fire at the PMV plant, which produces vinyl chloride monomer, also known as chloroethene, an industrial chemical used to produce plastic piping.

The incident occurred just weeks after three workers were killed and at least seven injured when a fire broke out on a Pemex oil-processing platform in the Gulf of Mexico.

It also came as Pemex fights to stem a slide in output that has hammered the company, and to implement deep cost cuts to cope with a sharp drop in oil prices. Mexico is trying to lure private investors to revive its oil industry.

Pemex, which enjoyed a decades-long monopoly over Mexico's oil and gas sector until an energy reform opened up the sector in 2014, has experienced a series of high-profile accidents.

In 2013, at least 37 people were killed by a blast at Pemex's Mexico City headquarters, and 26 people died in a fire at a Pemex natural gas facility in northern Mexico in September 2012.

A 2015 fire at its Abkatun Permanente platform in the oil-rich Bay of Campeche affected oil output and cost the company up to $780 million.

Pemex said last year it had reduced its annual accident rate in 2014 by more than 33 percent. But a Reuters investigation found that Pemex was reducing its accident rate by including hours worked by office staff in its calculations.