Four killed as fireball engulfs Mexico oil rig

Four people have been killed and at least 16 injured in a massive oil rig blaze in the Gulf of Mexico.

A ball of flame engulfed the rig, forcing workers to jump into the sea.

Helicopters helped evacuate 300 staff to the nearby city of Ciudad del Carmen.

Petroleos Mexicanos (Pemex), the state-owned oil company that runs the rig, said there was no evidence yet of a major oil spill.

Videos posted online showed enormous flames licking around the rig and lighting up the night sky.

One survivor from the Abkatun Permanente rig told the Associated Press that workers "jumped into the sea out of desperation and panic".

The fire broke out in the rig's dehydration and pumping area, said Pemex.

The company said there were eight firefighting boats attempting to quell the blaze.

A spokesman for Pemex told Reuters that the platform affected by the explosion produced about 40,000 barrels of oil per day.

Company President Enrique Pena Nieto said an investigation into the causes of the blaze was already under way.

Pemex has suffered a series of accidents over the past few years, with at least 37 people killed in an explosion at its 54-storey Mexico City headquarters in 2013 and another 26 killed in a fire at one of its natural gas facilities in September 2012.

The Gulf of Mexico saw one of the worst oil disasters in history when in 2010 part of the BP-owned Deepwater Horizon rig exploded, killing 11 and spilling an estimated 4.9 million barrels of oil into the sea.

The Abkatun rig lies off the coast of the states of Campeche and Tabasco.