Iranians angered by the sudden imposition of gasoline rationing have clashed with police and set fuel stations ablaze.
Fire department spokesman Behrouz Tashakor said 12 fuel stations were set on fire in the capital, Tehran.
Long lines began forming at fuel stations Tuesday evening as drivers tried to fill their tanks before the rationing took effect at midnight -- only a few hours after it was announced.
Riot police dispersed crowds shouting angry slogans denouncing Iranian President Mahmoud Ahmadinejad, who was elected on a platform of sharing the nation's oil wealth more evenly.
The gasoline rationing plan is aimed at reducing fuel imports and government subsidies.
Iran, the second largest oil producer in the Organization of Petroleum Exporting Countries, must import 40 percent of its fuel because it has low refining capacity.
Last month's gasoline price increase of 25 percent left the price of fuel in Iran at about 10 cents per liter, still some of the cheapest in the world.
Some lawmakers want to raise the price further, but others fear this could push inflation beyond what the poor could sustain.
Many Iranians regard heavy gasoline subsidies as a national right.
Some information for this report was provided by AFP and AP .