Nigeria’s huge new Dangote Industries refinery has gone out into the tanker term market in a bid to secure crude supplies.

Bloomberg reported that the facility near Lagos, which has a capacity of 650,000 barrels per day, has tendered to charter a vessel for three months, with three months of options after that, according to a company document.

The move by Africa’s biggest refinery, construction of which was completed last year, is the latest sign that the physical oil market is tightening, industry observers believe.