Nigeria's state-owned NNPC Ltd oil company said it has started the tender process for the operation of the Warri and Kaduna refineries, which are scheduled to begin processing crude this year.
The oil refineries, which are being upgraded after being shut for several years, have the capacity to process 125,000 barrels per day (bpd) and 110,000 bpd, respectively.
Nigeria, which is Africa's biggest oil producer, is seeking operators "to ensure reliability and sustainability towards meeting the nation's fuel supply and energy security obligations," NNPC said in a public notice on Thursday.
Warri and Kaduna are among state-owned refineries that have been mothballed for years, but which the government is trying to revive to end Nigeria's reliance on imported refined products.
The tendering process for the Port Harcourt oil refinery, in the Niger Delta, opened in January and is currently ongoing, the government said.
State-owned refineries will offer an alternative to the 650,000 bpd capacity Dangote refinery, built by Africa's richest man, Aliko Dangote, on the outskirts of Lagos. It is undergoing test runs for gasoline production, with full operation expected by mid-September.
(Reuters - Reporting by Isaac Anyaogu)