The product is normally stolen from pipelines in the oil-producing Niger Delta region and loaded into ships in the Atlantic Ocean from where it is sent abroad.
The navy has now been deployed to combat the crime.
Ships, gun boats and air force patrol planes were recently deployed for the first phase of the operation which lasted one week. Rear-Admiral Ameen Ikioda, who commands the western naval command, says the exercise marks the beginning of a long-term plan to combat oil theft.
"It is not just a one-off thing," he told RFI. "It is something that is going to be on a continuous basis now. We are going to intensify our efforts at ensuring that we maintain presence in that area.
"We hope to know where gaps exist and then know how to fill in the gaps so that we can be more proactive in dealing with issues that may arise from all these theft cases in the waters of the country."
The crime is carried out by syndicates which include Nigerians and international oil traders, who sell the stolen product to refineries around the world. The Anglo-Dutch company, Shell, the largest multinational oil company operating in Nigeria says it loses 12 million euros daily to oil thieves.
"The estimates we have seen, we have heard about and talked about is about 150,000 barrels a day," says Tony Attah, Shell's vice president of corporate affairs. "That comes to almost 15 million dollars [12 million euros] a day."
Most estimates put Nigeria’s annual loss at seven billion dollars (5.4 billion euros).
State-owned radio and television stations often carry public service announcements aimed at discouraging people from indulging in crude-oil theft. But many feel that neither public service announcements nor the recently launched military action will halt the crime.
Morris Alagoa of the Environmental Rights Action in Bayelsa State in the Niger Delta says local youths involved in oil theft are not likely to give up the crime because they say pollution caused by oil exploitation has affected their environment and their traditional occupations.
"According to them, their people can no longer fish as they used to do in those days, they can no longer farm, the lands have been polluted so they have seen tapping from the pipelines to either sell the crude or to refine what they have seen as one of the most thriving business within their local economy," he says. "So if they are now stopped they feel they will be frustrated."
Many Nigerians doubt the government’s ability to effectively stop oil theft.
The Nigerian media say it is difficult to combat the crime because influential Nigerians are involved.