Thousands marched in Nigeria's main northern city against fuel price increases, waving anti-government banners.
The rally was the latest in a series of labor union-led protests throughout Nigeria, the world's eighth largest oil exporter. The demonstrations were to culminate at the end of the end of the month with a rally in the capital, Abuja.
In an unusual move, the black-uniformed policemen assigned to Tuesday's protest march were ordered not to carry their usual assault rifles.
The government ordered price increases last month of up to 40 percent on fuels such as gas and diesel to try to bring the subsidized prices closer in line with the world market.
The price increases are making life harder for Nigerians, 70 percent of whom live on less than a dollar a day. Nigeria's poor will be badly hit by higher prices for kerosene, used for cooking, and inflation resulting from increased transport costs.
Labor unions say it is unfair for citizens to pay more for fuel in an oil-rich nation. Nigeria, though, has relied on massive fuel imports to meet domestic demand while state-owned refineries hit by corruption under previous governments have been producing well under capacity.
Despite strong opposition, President Olesegun Obasanjo is pushing ahead with an economic reform policy that has meant successive price hikes at the pump. Periodic increases have nearly tripled fuel prices during the six years of Obasanjo's government, the AP reports.