Brent crude futures fell 54 cents, or 0.81%, to close at $66.09 a barrel. U.S. West Texas Intermediate crude slipped 52 cents, or 0.82%, to settle at $63.15.
Both benchmarks, which traded close to their highest in two weeks in the previous session, lifted by a temporary cut in U.S.-China tariffs, fell after data from the Energy Information Administration showed crude stockpiles rose by 3.5 million barrels to 441.8 million barrels last week.
Net U.S. crude imports rose last week by 422,000 barrels per day, the EIA said.
API industry data also showed a large build of 4.3 million barrels in crude stocks last week, market sources said on Tuesday.
“Definitely, the crude build in the API numbers was not of help,” UBS analyst Giovanni Staunovo said of Wednesday’s oil price fall.
The Organization of the Petroleum Exporting Countries and allied producers, known as OPEC+, has been increasing supply to the market.
On Wednesday, however, OPEC trimmed its forecast for growth in oil supply from the United States and other producers outside the wider OPEC+ group this year.
“They are not changing their demand profile but adding more barrels,” said Bob Yawger, director of energy futures at Mizuho. “At some point, supply is just going to swamp out demand and drill the market lower.