Oil prices fell overnight after sources said OPEC may raise output from July if Venezuelan and Iranian supplies fall further and prices keep rallying.
Rising US crude stockpiles also dragged US futures down by more than $US1 a barrel.
West Texas Intermediate (WTI) crude fell $US1.03 to settle at $US63.58 a barrel.
Global benchmark Brent settled at $US70.83 a barrel, down 90 US cents.
“Now there is a suggestion that OPEC may surprise us and raise production pre-emptively if we get a price spike,” said Phil Flynn, an analyst at Price Futures Group in Chicago.
The Organisation of the Petroleum Exporting Countries may raise oil output from July if Venezuelan and Iranian supply drops further and prices keep rallying, because extending production cuts with Russia and other allies could overtighten the market, sources familiar with the matter said.
Venezuelan crude production has dropped below one million barrels per day (bpd) due to US sanctions, the International Energy Agency said on Thursday, even below the 960,000 bpd OPEC reported on Wednesday.
Iranian supply could fall further after May if, as many expect, the US tightens its sanctions against Iran.
OPEC and its allies led by Russia are due to meet in Vienna on June 25-26 to set their policy.
Overall output from OPEC, which has agreed with allies to withhold 1.2 million bpd of crude from the market since the start of 2019, fell 550,000 bpd in March to 30.1 million bpd, the IEA said.
The agency, which co-ordinates the energy policies of developed countries, recorded oil stocks in industrialised countries falling in February by 21.7 million barrels, putting inventories 16 million barrels above their five-year average.
Market concerns that OPEC could increase output compounded worries that US crude production is rising.
US crude inventories surged by 7 million barrels to a 17-month high of 456.6 million barrels last week, the Energy Information Administration said on Wednesday.
US crude oil production remained at a record 12.2 million bpd, making the United States the world’s biggest oil producer ahead of Russia and Saudi Arabia.
The surging production and regional refinery outages have depressed prices of cash grades, putting more pressure on US crude, said Bob Yawger, director of energy futures at Mizuho in New York.
US West Texas Intermediate crude at Midland on Thursday traded at the biggest discount to futures in almost four months after Phillips 66 closed a unit for maintenance at its Borger, Texas refinery, adding to a backlog of barrels as production climbs.
Selling accelerated on Thursday morning as US crude dropped below $US63.71 a barrel, a technically significant level at which some funds had stops in place, triggering automatic sales, Yawger said.