The feat was achieved weeks after a similar one was intercepted by naval operatives in Rivers waterways.
The barge, Dantech II, was suspected to have lifted the diesel from illicit refining facilities, which mainly operated in thick and swampy mangrove forests in the Niger Delta.
Operators of illegal refineries steal crude oil by breaking and connecting secondary pipes into pipelines operated by government and multinational oil companies.
Commander Tumi Ogunkoya, Navy Officer In-Charge of Federal Ocean Terminal Onne, Rivers, who led newsmen to the barge in Onne on Thursday, did not disclose the volume of diesel onboard Dantech II.
However, a reliable security source, with inside knowledge of the seizure, told NAN that the barge had about 1 million litres of adulterated diesel on it.
Ogunkoya said the barge was intercepted on March 29 by troops manning the Nigerian Navy Ship (NNS) Pathfinder gunboats, following intelligence gathering on operators of the barge.
“The NNS Pathfinder team arrested the barge, Dantech II, around Agip waterfront for suspected illegal bunkering activities.
“At the time of arrest, the barge was laden with unspecified quantity of substance suspected to be illegally refined Automotive Gas Oil (diesel).
“Consequently, the barge was towed to the NNS Pathfinder holding bay at Federal Ocean Terminal Onne for safekeeping and investigation,” he said.
Ogunkoya said no arrest was made as operators of the barges fled the scene on sighting advancing naval forces during the raid on Agip waterfront.
According to him, naval investigators have concluded their investigation having spent over three months establishing different leads into the matter.
He explained: “So, on completion of our investigation, the naval headquarters directed that the barge be handed over to the Economic and Financial Crimes Commission (EFCC) for further investigation.
“The navy urges perpetrators of these illicit acts to have a rethink and desist from committing maritime crimes before the long arm of the law catches up with them,” he warned.
The navy commander said that troops would continue to carry out 24-hour patrol as well as maintain presence at flash points in the about 33,000 creeks in the Niger Delta.
Miss Asikiye Lot, a Deputy Detective Superintendent of the Economic and Financial Crimes Commission (EFCC), received the barge on behalf of the anti-graft agency.