She said Saturday's leak on the Trans Ramos oil pipeline was confirmed "to have been caused by sabotage". The leak was later stopped.
No group has so far claimed responsibility for the attack.
It came shortly after Nigeria's militant group Mend said it was ending the truce it declared last October.
An alleged group spokesman said Mend did not believe the government would restore control of resources to local people.
Mend has demanded that residents be given a greater share in profits from oil resources and land.
It warned oil companies to prepare for what it called an all-out onslaught against installations and personnel.
Analysts later said it was not immediately clear if this statement came from the whole of Mend - the Movement for the Emancipation of the Niger Delta - or just a faction that did not accept the offer of an amnesty from Nigerian President Umaru Yar'Adua.
Militants have carried out a series of attacks which have cost Nigeria millions in lost revenue over the years.
The attacks have meant that facilities in the area have been unable to work beyond two-thirds capacity, costing $1bn a month in lost revenue.
