U.S. oil prices slid on Thursday, reversing early gains as a rebounding dollar weighed on commodities denominated in the U.S. currency.
Prices were already lower when market intelligence firm Genscape reported a build of more than 840,000 barrels in U.S. crude in the four days to April 19 at the Cushing, Oklahoma delivery point, traders who saw the data said.
The Genscape data further weighed on sentiment. Market players already were concerned that this month's 14-percent rally could coax U.S. shale crude producers to raise output.
Benchmark Brent crude futures fell $1.16 to $44.64 a barrel, off its session high of $46.18.
U.S. crude futures settled $1 lower, or 2.3 percent, at $43.18, having risen as high as $44.49.