The government hopes the refinery will turn Nigeria, Africa's biggest oil producer, from an importer of refined fuels to an exporter and put an end to recurring fuel shortages while creating tens of thousands of jobs.

The size of about 130 football fields, Dangote Industries has billed it as the world's largest single-train petroleum refinery, meaning it will have only one crude distillation unit.

The project, launched in 2017, is located in the Lekki area of Lagos State, off the Atlantic Ocean, and is expected to process 650,000 barrels of crude oil a day.

The refinery, 20%-owned by the state, is not expected to operate at full capacity until 2024.

"At full capacity it can meet 100% of the Nigerian requirement of all refined products and also have surplus for export," Dangote Industries said in a statement last week.

Mr Buhari is commissioning the plant in one of his last public acts before he steps down as president next Monday following two terms in office.

He will hand power to Bola Tinubu, who won disputed presidential elections in February.

Nigerian oil and gas consultant Henry Adigun told the BBC that today's event was "more political than technical".

"There is still a lot more work to do in terms of permits and licences. I don’t think the refinery is at the stage where we will start enjoying the benefit as Nigerians," he said.