Nigeria’s state-owned oil company, Nigeria National Petroleum 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 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.

Nigeria has issued a new tender for 15-20 cargoes for delivery in September and October but some traders are reluctant to participate, saying they still haven’t been paid for the last one.

“People are finding it very difficult to carry NNPC. If they can’t get payment some of the smaller suppliers won’t be able to get credit,” said a downstream consultant specialising in West Africa, who asked not to be named.

For now, Nigeria is well-supplied with refineries running at least 50 percent of capacity and high offshore stocks, an NNPC spokesman said in August. Trade sources estimate there are now around 30 cargoes held in tankers waiting to unload in the Gulf of Guinea. Demand for the fuel also tends to be lower during the summer wet season as wet weather deters motorists and often leads to waterlogged roads.

But supplies could quickly tighten once fuel demand picks up, traders said. Consumption can rise to around 35 million litres a day or 25,000 tonnes in the peak season which is nearly the equivalent of a standard size 33,000 tonne gasoline tanker.

“Come the November, December, January peak season, 30 cargoes can be knocked out pretty quickly,” said a Lagos-based physical gasoline trader. Nigeria is due to hold elections in January and the government will be keen to avoid serious fuel shortages and price rises that have sparked widespread strikes in the past. “If there’s no financial cover to bring in petrol for Nigeria, what’s it going to be like before the elections?”