The US Bureau of Safety and Environmental Enforcement said the fire broke out late yesterday aboard the Hercules 265 Rig located some 88 kilometres off the Louisiana coast, in the Gulf of Mexico.
The fire ignited after a leak which prompted the evacuation of the rig's 44 workers, authorities said.
"The natural gas leaking from the well ignited at 10:50 pm CDT July 23, 2013. No one was on board at the time of the ignition and no one was injured," the BSEE said in a statement to AFP.
Authorities said that a firefighting vessel was trying to extinguish the blaze using water and foam.
The US Coast Guard, which is providing safety management oversight, dispatched a 27-metre long cutter and crew, a helicopter, and a twin engine aircraft to the scene.
The BSEE said that the site operator, Walter Oil and Gas Corporation, will be conducting a site assessment prior to beginning any work on the well.
British energy giant BP reached a USD 7.8 billion settlement last year with thousands of people and businesses hit by the Deep Horizon explosion and oil spill -- the worst environmental disaster in US history.
