A move by the Nigerian government to scrap fuel subsidies and to hike petrol prices to more than double has drawn fire from people in the oil-rich African country.
Hundreds of people held a protest rally in the capital, Abuja, and other cities on Monday to protest at the removal of fuel subsidies.
Police used tear gas and made arrests to disperse angry protesters.
Ordinary Nigerians and trade unionists condemned the government and vowed to plan more protests and strikes in the coming days.
Fuel prices have increased from 65 naira (USD 0.40) per liter to at least 140 naira in gas stations at a time when many Nigerians, the majority of whom live on less than USD 2 per day, already find basic commodities too expensive.
A member of OPEC, Nigeria produces about 2.4 million barrels of oil per day, but virtually all of its petroleum products are imported due to corruption, mismanagement and violence at its refineries.