The oil market swirled again Wednesday when OPEC reduced its estimate of 2015 demand, and a U.S. government agency said domestic refineries took advantage of declines in crude prices to process more oil than any time since data began to be collected in 1989.

Kuwait offered new discounts to Asian customers, and the Saudi Arabian oil minister questioned the need for a production cut.

"Why should I cut production?" Ali Al-Naimi, the oil minister, said in response to reporters' questions Wednesday in Lima, Peru, where he is attending United Nations climate talks. "This is a market and I'm selling in a market. Why should I cut?"

The Organization of Petroleum Exporting Countries cut the forecast for how much crude it will need to produce next year by about 300,000 barrels a day to 28.9 million a day, the least since 2003. OPEC said in its monthly report that demand for its crude is weakening amid expanding supplies from U.S. shale producers. The group's three largest members, Saudi Arabia, Iraq, and Kuwait, are offering oil to Asian buyers at the deepest discounts in at least six years.

West Texas Intermediate crude oil plunged 4.5 percent to settle at $60.94 a barrel, while Brent fell below $65 for the first time since 2009.

Saudi Arabia is the world's largest oil producer and has saved revenue from previous sales, so it can withstand price declines. But other oil-producing nations - inside and outside OPEC - depend on higher prices to sustain their current budgets.

"Naimi can't change policy within two weeks of an OPEC meeting. They've got to stick it out for at least a quarter to make it obvious that non-OPEC can't rely on high and stable prices," Paul Horsnell, head of commodities research at Standard Chartered plc, said from London.

Any break in OPEC solidarity or a price war will lead to an "enormous price-dive shock" that would push oil to $40 or $50, Mohammad Sadegh Memarian, an Iranian Oil Ministry official, said at a conference in Dubai on Tuesday.

"Saudis' paradigm shift clearly shows their frustration with increasing supplies globally, OPEC and non-OPEC both," Abhishek Deshpande, an analyst in London at Natixis S.A., said by e-mail.

Refiners in the United States processed the most oil ever last week, taking advantage of crude prices' tumbling to a five-year low.

Plants processed 16.6 million barrels a day of crude in the week ended Friday, the most in Energy Information Administration data going back to 1989. The access to cheaper domestic crude and natural gas has enabled U.S. refiners to increase operating rates to above 95 percent for the first time since 2005, increasing gasoline supply and driving down prices at the pump to the lowest level in more than four years. Refineries have used more crude in each of the last six weeks as seasonal turnarounds wound down.

"Prices are going down and production is going to continue rising," said Tom Finlon, Jupiter, Fla.-based director of Energy Analytics Group L.L.C. "The crude needs to be processed into fuels consumers use and the refiners are in that business. They're ready after performing seasonal maintenance."

Gasoline supplies rose by 8.2 million barrels to 216.8 million in the week ended Friday, the biggest gain since the week that ended on Sept. 21, 2001. Inventories of distillate fuel, a category that includes diesel and heating oil, climbed 5.58 million to 121.8 million, the biggest increase since January.

Pump prices slipped 1.6 cents to $2.64 a gallon nationwide yesterday, the lowest since February 2010, according to AAA.