A rallying dollar punished oil on Tuesday as players took profit on recent highs in the spread between Brent and U.S. crude, traders said.
In New York, U.S. West Texas Intermediate crude closed down $1.71, or 3.4 percent, at $48.29 a barrel, weighed by the dollar and expectations that U.S. crude inventories had swelled to another record high last week from new supply builds.
, the London-traded global oil benchmark, slumped about 4 percent as expectations of a mid-year U.S. rate hike sent the dollar soaring to multi-year highs, making commodities denominated in the greenback costlier for holders of other currencies.
Brent was down $2, or 3.7 percent, at $56.50 a barrel.
Traders said WTI saw less pressure than Brent as players bet on a further narrowing of its discount to the London benchmark after forecasts for a modest build last week in the Cushing, Oklahoma delivery point for U.S. crude versus the rest of the country.
"The dollar's might is creating unexpected headwinds for oil. Brent particularly is taking it harder than WTI as people unwind and take profit in the spread between the two," said Tariq Zahir, managing member at Tyche Capital Advisors in Laurel Hollow in New York.
The Brent-U.S. crude differential fell to a 3-week low under $8 a barrel earlier on Thursday. The spread had narrowed by nearly 40 percent since hitting an end-February peak of $13, its highest in 13 months.
Carsten Fritsch, an oil analyst at Commerzbank, cautioned about a capitulation in Brent prices once it went below key support level $57.80.
"Brent is looking increasingly heavy with a decline likely to lowest levels in almost four weeks expected within the next couple of sessions," oil analysts at Jefferies Futures said in a note.
According to a Reuters survey, U.S. crude stocks are set to extend their record build for a ninth week.
Investors are waiting for weekly inventory reports from industry group the American Petroleum Institute later on Tuesday, and official stockpile numbers from the U.S. government's Energy Information Administration on Wednesday.
Also on Tuesday, the EIA revised upward its 2015 domestic oil production outlook, but lowered its 2016 forecast because it expects the slump in global prices to weigh on the country's shale boom next year.
Expected total oil production in 2015 will rise to 9.35 million barrels per day, slightly higher than the 9.3 million bpd forecast last month, the EIA said in its monthly short-term energy outlook.
The revision comes a day after the EIA released data showing that oil production from U.S. shale fields will grow at its lowest pace in over four years starting in April, on the back of low prices and company spending cuts.
An EIA spokesman said the revision is due to an increase in baseline expectations for the fourth quarter and to production in the Gulf of Mexico. Offshore production in the Gulf is more resistant to price swings than onshore production as it requires longer-term investment.
Meanwhile, 2016 total oil production was expected to slip to 9.49 million bpd from 9.52 million bpd in last month's report, the EIA said.