Nigeria's biggest trade union is threatening a nationwide strike over rising fuel prices.
Nigeria's oil exports could be disrupted
The Nigerian Labour Congress (NLC) said its members would down tools for 21 days from Wednesday unless the government agreed to cheaper fuel.
"Banks, offices, schools, markets and companies will be closed," said NLC leader Adams Oshiomole.
Nigerian fuel prices have risen sharply since the government cut subsidies and de-regulated the market last year.
The move triggered a long-running confrontation between the government and trade unions protesting over the economic hardship caused by dearer fuel.
Cost of living
The unions claim higher prices have pushed up the cost of public transport and food in a country where most of the 130-million strong population subsists on less than a dollar a day.
The latest strike threat centres on a surge in average prices from about 42 naira ($0.30) to between 50 and 55 naira in late May.
The government has taken legal steps to prevent the threatened industrial action, issuing a court summons against the NLC and the affiliated Trade Union Congress.
The unions have said they will appear in court, but have pledged to proceed with the strike regardless.
"Court order or no court order, Nigerian workers will go on strike from Wednesday unless the government reverts to the pre-May price," Mr Oshiomole said.
"Nigerians are advised to use today and Tuesday to stockpile foods and provisions at home."
There are also fears that the strike, supported by oil workers' unions Pengassan and Nupeng, could disrupt Nigeria's oil exports.
"There won't be activities on the rigs. Loading will not take place at the terminals," a Pengassan official told the Agence France Presse news agency.
Nigeria, Africa's biggest oil producer and a member of the Opec cartel, pumped 2.7 million barrels of oil a day last month, compared with global daily demand of about 73 million barrels.
Razia Khan, Africa analyst at Standard Chartered bank, told the BBC that any disruption to Nigeria's exports would reinforce fears of global shortages, which last week pushed US oil prices to a record high of over $42 a barrel.
"Disruption would mean further pressure on the price of oil internationally," she said.
Ms Khan added that the continuing stand-off between government and trade unions illustrated the political sensitivity of fuel prices in Nigeria.
"It's almost seen as a birthright to have access to cheaper fuel," she said.
Nigeria's unions staged an eight-day strike, punctuated by sporadic rioting, in July 2003, but two subsequent planned walkouts - in October last year and January 2004 - did not materialise.