The BBC’s Mark Lobel in Lagos says banks, shops and businesses are shut.
Nigerian unions have launched a nationwide strike over the elimination of a government fuel subsidy.
Correspondents say the strike is likely to bring parts of the country, Africa’s largest oil exporter, to a standstill.
There have been angry protests since the subsidy ended on 1 January as fuel and transport costs have doubled.
Members of parliament have called on President Goodluck Jonathan to reconsider, but he has said the subsidy was economically unsustainable.
The two main union organisations behind the strike have said as many as eight million Nigerians will not go to work.
The unions vowed to press ahead with the indefinite general strike despite a court order restraining them from it.
‘Business as usual’
The normally bustling streets of Lagos are quiet, say correspondents, with the exception of police patrols and protesters on their way to rallies.
Shops, banks and offices are all shut, says the BBC’s Mark Lobel in Lagos.
Hundreds of people at a mass rally in Lagos are screaming and singing out against the fuel subsidy removal they say is totally unfair.
The protests are gathering pace – and the unions say the strike will go on indefinitely.
“Bad luck Jonathan” many of the protesters cry. They have a point.
The timing could not be worse for President Goodluck Jonathan, who said his fight against militant Islamists of Boko Haram in the north, who have recently killed dozens of Christians, is worse than the country’s civil war in the 1960s.
He even suggested government officials may be secret members of the group.
It was the president who chose the timing of this fuel fight but it may be that the growing unrest in the north forces his hand in this struggle too.
He can not afford state resources being stretched for too long while the attacks in the north continue.
In Abuja, pickets have closed the airport, preventing flights from arriving or leaving, says the BBC’s Ibrahim Shehu Adamu in the Nigerian capital.
Also in Abuja, there are reports that youths camping in the city’s Eagle Square were cleared out overnight by police using tear gas.
In the northern city of Kaduna, there is a heavy police presence and the streets are quiet, with all shops closed, says the BBC’s Abdullahi Kaura Abubakar.
AFP news agency said police in the main northern city of Kano fired tear gas and shots in the air to disperse thousands of protesters who were converging on the governor’s office.
Speaking shortly before the strike was due to officially begin, Finance Minister Ngozi Okonjo-Iweala said she expected a low turnout.
“Even in Abuja… most people are going to work. In Lagos, a lot of associations and schools say they’re going to carry on business as usual,” she told the BBC’s Network Africa.
Ahead of the strike, there were long queues at petrol stations as motorists and users of generators tried to stock up on fuel.
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A similar strike in 2003 saw Nigeria almost entirely shut down – and the government back down, reducing rather than scrapping the subsidy.
While the strike is expected to affect oil workers too, industry sources do not expect the industrial action to significantly affect crude exports, Reuters news agency reports.
The loss of the fuel subsidy has angered many Nigerians, who saw it as the only benefit they received from the country’s vast oil wealth.
Nigeria’s fuel prices
- Previous price in petrol stations: $0.40/ litre
- New price in petrol stations: $0.86
- Previous black market price: $0.62
- New black market price: $1.23
- Annual cost to government of subsidy: $8bn
Most of Nigeria’s 160 million people live on less than $2 (£1.30) a day, so the sharp price increases have hit them hard.
“With these increases, the cost of transport has gone up and this has also affected the cost of food, and the basic necessities of life, such as rents, school fees and medical bills,” said Chris Uyot, a spokesman for the Nigeria Labour Congress, one of the strike’s organisers.
“Everything’s up – everything’s up and the wage level in Nigeria is very low. So the issue now is how do they expect these millions of Nigerians, we are talking about over 70% of Nigerians, how are they going to survive?”
Despite being a major Opec oil producer, Nigeria has not invested in the infrastructure to produce refined fuel, so has to import much of its petrol.
With the subsidy, fuel was much cheaper in Nigeria than neighbouring countries, so some of it was smuggled abroad.
President Jonathan made a televised address on Saturday to defend the removal of the subsidy and other government austerity moves.
“We must act in the public interest, no matter how tough, for the pains of today cannot be compared to the benefits of tomorrow.”
The deregulation of the petroleum sector was, he insisted, the best way to curb corruption and ensure the survival and growth of the economy.
“The truth is that we are all faced with two basic choices… either we deregulate and survive economically, or we continue with a subsidy regime that will continue to undermine our economy and potential for growth, and face serious consequences.”
He said that top government officials would, from this year, take a 25% pay cut, and foreign trips would also be reduced.
The government says it will spend the $8bn (£5bn) it saves each year by scrapping the subsidy on improving health, education and the country’s erratic electricity supply.
However, many Nigerians fear it is more likely to end up in the pockets of corrupt officials.
Last month, International Monetary Fund head Christine Lagarde praised President Jonathan’s efforts to reform the Nigerian economy but cautioned that the country should become less reliant on oil exports for revenue.