YENAGOA, Nigeria (Reuters) -Nigerian energy firm Aiteo has shut down all oil production at its Nembe Creek facility, nearly 50,000 barrels per day of output, after detecting a leak, the company said on Wednesday.

Aiteo Eastern E&P said the leak was reported on Monday during routine operations in the Nembe area of Nigeria's oil-rich Bayelsa state. It is one of the most polluted places on Earth after decades of spills that have hurt farming and fishing.

The Nembe Creek facility is the largest of 11 fields under an oil mining lease operated by Aiteo, which also produces significant natural gas volumes that supply the Nigeria LNG plant at Bonny Island.

The leak's cause was undetermined, Aiteo said, adding that the shutdown was precautionary while it contained the spill.

Aiteo said it has notified regulators.

"While we regret the production losses ... and the potential environmental impact, our current priority is to expedite an efficient spill-management process in line with regulatory standards and collaborate with all stakeholders to restore production and mitigate associated risks," said Aiteo Managing Director Victor Okoronkwo.

Solomon Ukponevi, head of the country's oil-spill detection and response agency NOSDRA, said an investigation was underway.

In Nigeria, Africa's biggest oil producer, oil spills have had a catastrophic impact on communities where people have no other water supply than creeks and rely on farming and fishing.

Oil spills, sometimes due to vandalism or corrosion, are common in the Niger Delta, a vast maze of creeks and mangrove swamps crisscrossed by pipelines and blighted by poverty, pollution, oil-fuelled corruption and violence.

(Reporting by Tife Owolabi; writing by Chijioke Ohuocha; editing by Jason Neely, Elisha Bala-Gbogbo, Sharon Singleton and Rod Nickel)

By Tife Owolabi