Aliko Dangote has asked Nigeria to suspend imports of diesel and aviation fuel in a move that would hand his refinery a monopoly on their sale, the head of the country’s regulatory agency said.

“That is not good for the nation in terms of energy security and that is not good for markets in terms of monopoly,” Farouk Ahmed, head of the Nigerian Midstream and Downstream Regulatory Agency, told reporters in remarks shared on social media.

A spokesman for Dangote declined to comment.

Africa’s richest person controls a massive 650,000 barrel-a-day refinery outside Lagos, the commercial capital, producing aviation fuel, naphtha, and diesel. It became operational in January.

The request follows complaints by a Nigerian fuel marketing lobby that the regulator was restricting imports of high-sulphur diesel while allowing it to be domestically produced.

In a letter to Nigerian lawmakers seen by Bloomberg, they said this favored Dangote because of a lack of local competition, characterizing it as an “apparent tilt towards the creation of a monopoly” for his refinery.

A spokesman for the regulator said the permissible sulphur content for imported diesel was 50 parts per million, but local refineries including Dangote are allowed to produce diesel with between 650 and 1,200 ppm.

Fuels with high sulphur content can damage engines and are bad for the environment. They are banned in some parts of the world.

“This is a clear adoption of Dangote Oil Refinery as the sole supplier of automotive gas oil to the nation,” the Depot and Petroleum Products Marketers Association of Nigeria said, referring to diesel. “This situation is detrimental not only to the downstream operators but to the nation as large.”

Bloomberg