The threat of higher fuel prices has provoked panic-buying and traffic jams in Lagos, Nigeria.
Long queues are forming at filling stations
Nigeria's President Olusegun Obasanjo said on Sunday that his government is considering cutting fuel subsidies.
The money spent on keeping petrol cheap, he said, would be better spent on better education and healthcare for the poor.
But Nigeria's trade unions are opposed to fuel price rises, which they say would hurt the living standards of ordinary people.
Petrol prices are an especially sensitive issue in Nigeria, because there is growing resentment that oil revenues have done little to help overcome the country's poverty.
And the leadership of the National Labour Congress has threatened strike action if the price rises go ahead.
Nigeria's president said the state was spending almost 250 billion naira ($2bn; £1.1bn) to keep petrol prices artificially low.
"That money is not going into the pockets of poor people. It is going into the pockets of some rich people who are getting richer," he added.
If I have 250 billion naira I will do more on education... It will reach poor people
President Olusegun Obasanjo
"If I have 250 billion naira I will do more on education. It will reach poor people. I will do more on health," the president said, mentioning some of the themes of his election campaign.
Nigerians are heavily dependent on private cars for transport because the country's urban public transport system is poor.
Although Nigeria ranks as one of the world's leading oil exporters, smuggling of fuel for export has created widespread petrol shortages.
Motorists can face long queues at petrol stations and black market prices can be more than three times the official price of 26 naira (20 cents) a litre.
Efforts to curb the illegal trade would be "helped greatly by increasing the fuel price at the pumps," the BBC's Lagos correspondent Dan Isaacs said.
He said foreign economists have recommended that the Nigerian authorities should cut subsidies to discourage smugglers.
Previous attempts to raise fuel prices have been greeted by uproar and riots.