The pump prices for petrol may fall if rules are relaxed in California, New York and Connecticut, which have asked the US Environmental Protection Agency (EPA) to waive requirements for specially blended petrol this summer because the states have not met federal air pollution guidelines.
"It's my understanding that EPA is seriously considering looking at this request," US Energy Secretary Spencer Abraham told a Congressional committee on Thursday.
An EPA spokesman confirmed the agency is considering the requests but has set no time frame for action.
The US currently has record high petrol prices, with the pump price of regular fuel averaging US$1.76 per gallon, according to the US government.
Californians are paying about US$2.13 per gallon for self-serve regular petrol, which is the highest in the nation.
New York's average petrol price is about US$1.87 a gallon and it is about US$1.81 in Connecticut, according to the American Automobile Association, a motorists' group.
US light crude ended at US$34.27 a barrel, down US$1.49 on the day.
US oil prices were already down about 50 cents when the news of the possible petrol waivers emerged.
The oil market reacted sceptically to the Opec cartel's Wednesday agreement to implement a previous commitment to tighten supply by 1 million barrels per day beginning Thursday. Market participants say they do not expect Opec to fully implement its cut.