The Dangote Petroleum Refinery located in the Lekki area of Lagos has began operation.
A source told journalists that the refinery began production in the early hours of Friday.
This followed the delivery of six million barrels of crude supply to the facility earlier this week.
Former President Muhammadu Buhari commissioned the 650,000 barrel-per-day refinery on May 22, 2023.
The refinery sits on 2,635 hectares (6,500 acres) of land at the Lekki Free Zone in Lagos and costs about $19 billion.
Regarded as the largest single-train refinery in the world, the facility will begin operation with the production of diesel and aviation fuel before moving on to petrol.