Nigeria’s state-owned oil company NNPC owes gasoline suppliers between $3 billion and $6 billion for previous imports, trade sources told Reuters, although the company said it was meeting its obligations.

NNPC representatives came to London in July to assure suppliers that the company would pay off a significant portion of the backlog by the end of August, trade sources said.

“What is going on is very normal. We have a programme of repayments .... Evidence of that is the abundance of product available in Nigeria. We are meeting all our obligations,” NNPC spokesman Levi Ajuonoma told Reuters late last week, when asked to comment on the remarks from the trade sources.

“Our suppliers are very happy with us ... If at any point in time there are delays, they know that these things are just normal in the course of this kind of business. There is no cause for concern.”

The July meeting took place shortly after Nigeria’s then minister of state for finance said the company was insolvent, comments that were subsequently contradicted by three cabinet ministers.

NNPC said it had a healthy cash flow but acknowledged that unpaid government subsidies were putting it under financial strain. Although Nigeria is Africa’s largest oil and gas producer, its four refineries often run at low rates because of poor maintenance and sabotage of facilities.

Even if they were to run at full capacity, the refineries could only meet about a quarter of the country’s imports, leaving it reliant on mostly European suppliers.