The Nigerian army confirmed an explosion on Monday at an oil facility owned by Royal Dutch Shell in southern Nigeria, but denied militant claims that 11 soldiers had been killed.
Lieutenant Colonel Musa Sagir told AFP that a "riser" near a flowstation in Degema in the Niger Delta region had "exploded in the early hours".
Shell has yet to make a formal statement on the incident.
"The cause of the explosion is not yet verified. But we suspect that explosives might have been used by miscreants to carry out the explosion," Sagir added.
He had previously insisted there had been no militant attack on any pipeline.
The most high-profile armed group in the region, the Movement for the Emancipation of the Niger Delta (MEND), earlier Monday said it had sabotaged a Shell pipeline at the Awoba flowstation in Degema and killed 11 soldiers in a shootout.
Sagir insisted that no soldiers had been killed.
