The West Texas Intermediate for October delivery lost 94 cents to settle at 67.42 U.S. dollars a barrel on the New York Mercantile Exchange. Brent crude for October delivery decreased 1.18 dollars to close at 71.07 dollars a barrel on the London ICE Futures Exchange.
The slide marked the first among the past four sessions this week.
Oil prices also came under pressure amid strength in the U.S. dollar. The dollar index, which measures the greenback against six major peers, rose 0.25 percent to 93.0530 in late trading on Thursday. Historically, the price of oil is inversely related to the price of the U.S. dollar.
Traders continued to digest the U.S. fuel inventory data.
U.S. crude oil inventories decreased by 3 million barrels during the week ending Aug. 20, the U.S. Energy Information Administration (EIA) said in a report on Wednesday.
According to the EIA, total motor gasoline inventories decreased by 2.2 million barrels last week, while distillate fuel inventories increased by 0.6 million barrels.