U.S. crude settled at a more than six-year low on Tuesday after China's currency devaluation raised questions about oil demand from the No.2 consumer, and a new OPEC estimate showed non-member producers were likely to keep output high despite low prices.
A BP refinery outage in Whiting, Indiana that could last at least a month, idling some 240,000 barrels per day of crude distillation, added to the bearish sentiment, traders said.
U.S. crude fell $1.88, or more than 4 percent, to $43.08 a barrel, its lowest settlement since March 2009, and about $1 above the 2015 contract low on March 18.
Brent fell $1.23, or 2.4 percent, to $49.18 a barrel, paring more than half of its gains in a rally on Monday.
"It's time to sell any and all rallies," said Tariq Zahir, managing member at Tyche Capital Advisors in Laurel Hollow in New York, who bets on crude hitting $30 a barrel or lower.
China depreciated its yuan currency by nearly 2 percent after a run of poor economic data, guiding the currency to a near three-year low.
The Organization of the Petroleum Exporting Countries projected that crude supplies from countries outside the group will rise by 90,000 bpd this year, sign that crude's price collapse was taking longer than expected to hit U.S. shale drillers and other competing sources.
A global oil oversupply since last summer, led by stubbornly strong U.S. shale crude output and record output by Middle East producers, have driven prices down from June 2014 highs above $100 a barrel.
This year so far, U.S. crude has lost almost 20 percent, extending the 46 percent drop in 2014. Brent has fallen 15 percent, adding to last year's 48 percent tumble.
While weekly inventory numbers for U.S. crude have sometimes come in below expectations and bumped up prices, they have not sustained a price recovery.
The American Petroleum Institute, an industry group, will issue its report for last week's inventories at 4:30 p.m. (2030 GMT).
Analysts polled by Reuters forecast a 1.8 million-barrel decline on average from the previous week. Official data on stockpiles are due on Wednesday at 10:30 a.m.
(By Barani Krishnan; Additional reporting by Ron Bousso in London and Henning Gloystein in Singapore; Editing by Dale Hudson, Bill Rigby and Marguerita Choy)