A blaze caused by an explosion on an oil storage vessel sparking fears of an environmental disaster off Nigeria's southern Delta state has been  brought under control, the government said Friday. 

"The fire was stopped last night," Idris Musa, director of the National Oil Spill Detection and Response Agency told AFP by phone, adding an investigation team was scheduled to deploy to the scene over the weekend.

Despite being Africa's largest crude producer, accidents are frequent in Nigeria's oil and gas industry, although they usually occur on land. 

Environment Minister Sharon Ikeazor described the incident as "worrisome" in a Tweet and said  a cooperative of oil companies was responding at the scene "to protect (the) vulnerable ecosystem".

The fire aboard the FPSO Trinity Spirit -- a floating production, storage and offloading vessel -- started "following an explosion during the early hours of Wednesday," the operator, Shebah Exploration & Production Company Ltd (SEPCOL) said in a statement on Thursday.

It was unclear how much oil was stored at the time of the explosion and whether oil had started spilling into the waters.

The company's chief executive Ikemefuna Okafor said there were "no reported fatalities" but confirmed "there were 10 crewmen onboard the vessel prior to the incident."