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

The blast, which threw 13 people into the water, was reported by a commercial helicopter company about 0930 local time (1330 GMT).

The platform, reportedly still on fire, was not producing oil or gas, the Department of Homeland Security said.

Helicopters, boats and aircraft were en route to the site.

The blast occurred around 130km (80 miles) south of Vermilion Bay along the central Louisiana coast.

All 13 workers who fell into the Gulf are accounted for, the Coastguard said. One person is reportedly injured.

" are all wearing some sort of an immersion suit that protects them from the water," Coast Guard chief petty officer John Edwards told MSNBC

The platform is owned by Mariner Energy and is located in approximately 2,500ft (762m) of water, the Coast Guard said.

"Right now we're focused on search and rescue and then, ultimately, as this thing progresses we're going to be looking into the cause," Mr Edwards said.

Seven Coast Guard helicopters, two planes, and three cutters were sent to the site of the explosion from the states of Louisiana, Texas, and Alabama.

The latest explosion comes more than four months after an blast ripped through a Deepwater Horizon rig run by BP, causing about hundreds of million gallons of oil to be released into the Gulf of Mexico.