"A number of incidents that involved oil leaks happened yesterday (Tuesday) at the Adibawa flowstation. We had to shut it down to allow for repairs to take place. Repair teams are being mobilised to the site," he told AFP.

"The cause of the leaks is yet unknown. An investigation is going on to determine what really happened," he added.

Okonedo declined to give figure of how much production would be lost from the shut down.

"We do not give out production figures," he said.

He also declined to comment on the allegation that the leaks happened after some local youths employed to protect pipelines around the area were sacked.

"I know we have surveillance contractors and community members across the Niger Delta to watch over these facilities. But I cannot comment on the speculation that their services were terminated. The investigation will reveal what has happened," Okonedo said.

Protesters blocked facilities belonging to oil giant Shell last month in the same home state of President Goodluck Jonathan.

They were demanding improvements to communities in the area, including new roads and stable electricity supply.

They had accused Shell of breaching a 1999 accord on the provision of electricity and roads for the Oruma, Otuasega, Elebele and Imiringi communities in the state.

Shell denied the charge.

Separately, Shell on Wednesday accepted responsibility for two devastating oil spills in the Niger Delta in 2008 and 2009 which lawyers say have destroyed the livelihoods of a fishing community.

Nigeria is Africa's largest oil producer, but the main oil region, the Niger Delta, where Bayelsa state is located, remains deeply impoverished.

Copyright AFP (Agence France-Presse), 2011