Explosion on Mariner Energy oil rig in Gulf of Mexico

An explosion has torn through an offshore oil platform in the Gulf of Mexico, west of the site of a blast in April which caused a huge oil spill.

All 13 crew on the rig, operated by Marine Energy, escaped into the water and were later rescued.

The US Coast Guard said a blaze burned for hours after the explosion but had now been extinguished.

Officials said there was no evidence of an oil leak, despite earlier reports of a mile-long sheen on the ocean.

But the incident has led to criticism that lessons were not learned from the BP Deepwater Horizon disaster in April.

Seven Coast Guard helicopters, two planes, and three boats were sent to the site, about 80 miles (130km) south of Vermilion Bay along the central Louisiana coast, but the fire was reported to have been put out after several hours.

"The fire is out, and Coast Guard helicopters on scene and vessels on scene have no reports of a visible sheen in the water," Capt Peter Troedsson told a news conference in New Orleans.

"There's no report or any evidence of leaks, but we continue to investigate and to monitor that situation to make sure that that doesn't change," he added.

The explosion was first reported at 0930 local time (1330 GMT). It had started on an upper deck of the platform where living quarters were, a company official said, but the cause is not yet known.

Mariner Energy said the rig was undergoing maintenance and not producing any oil or gas at the time of the explosion.

'Presence of mind'

All 13 workers who jumped into the Gulf from the platform were picked up from the ocean by the Crystal Clear, an oil support vessel operating in the area, and taken to hospital on shore. Mariner Energy said none of them was injured.

The workers "had the presence of mind, used their training to get into those gumby suits [survival suits] before they entered the water", said Coast Guard chief petty officer John Edwards.

The captain of the Crystal Clear, Dan Shaw, said the men had been in the water for about two hours when he reached them, holding hands to stay together.

"We gave them soda and water, anything they wanted to drink. They were just glad to be on board with us," he told AP.

The federal government had earlier said that it would respond if there were reports of pollution.

The explosion comes four months after a blast ripped through the Deepwater Horizon oil rig leased by BP, causing hundreds of millions of gallons of oil to be released into the Gulf of Mexico.

Environmentalists have said the incident shows that lessons were not learned from that disaster.

"The BP disaster was supposed to be the wake up call, but we hit the snooze button. Today the alarm went off again," Michael Brune, executive director of US environmental group the Sierra Club, said in a statement.

"The oil industry continues to rail against regulation but it's become all too clear that the current approach to offshore drilling is simply too dangerous."

The Mariner platform is located in shallow water, approximately 340ft (105m) above the floor of the Gulf. Officials stressed if oil were to leak, the response would be much easier than in the Deepwater Horizon spill.

Louisiana Governor Bobby Jindal said the company had told him the seven active wells under production by the platform were shut down shortly after the fire broke out.