Many petrol stations remained closed in the capital Abuja Wednesday, after a strike that began there last week over the non-payment of subsidies by the government, while the action could soon widen to other parts of the country.

In the economic capital Lagos, an initial rush at some petrol stations on Wednesday due to panic buying died down later in the day.

The government has pledged to carefully vet fuel subsidy payments after investigations revealed massive corruption in the programme. Last week, it accused petrol importers under investigation of being behind the strike in Abuja.

The latest union to threaten a strike was the National Union of Petroleum and Natural Gas Workers (NUPENG), which includes tanker drivers who transport fuel across Africa's most populous country and top oil producer.

It claims some 15,000 of its members have not been paid by petrol sellers and has called for a nationwide strike to begin Friday. Government officials and the union were to hold talks Wednesday evening.

"The outcome of today's meeting at the federal ministry of labour in Abuja will determine if the strike will still go ahead," NUPENG President Igwe Achese told AFP.

NUPENG claims the government is to blame for the salary backlog because the authorities have not made fuel subsidy payments to petrol sellers, who have then claimed they cannot pay tanker drivers because of cash shortages.

To make fuel affordable, Nigeria has frozen the price of a litre at 97 naira ($0.60), lower than market rate, and fuel sellers expect subsidy payments from the government to make up the difference.

However, the subsidy programme has been found to be rife with corruption, including false claims and overpayments.

In April, a parliamentary probe said Nigeria lost $6.8 billion (5.3 billion euros) between 2009 and 2011 through the subsidy programme.

"It is clear that those behind the strikes are marketers being investigated for possible fraud," the finance ministry said in last week's statement.

"These elements have now resorted to hiding behind the unions to unnecessarily antagonise government and create hardship for Nigerians."

In January the government tried to end fuel subsidies, causing petrol prices to more than double, but was forced to partially reinstate them after a general strike and protests that brought tens of thousands of people into the streets.

Despite Nigeria's huge oil reserves, it imports much of its fuel due to a lack of refining capability -- a situation blamed on corruption and mismanagement.