The West Texas Intermediate (WTI) for July delivery shed 3.26 U.S. dollars to settle at 36.34 dollars a barrel on the New York Mercantile Exchange. The decline marked the biggest one-day loss since April 27 and the settlement was the lowest since June 1, according to Dow Jones Market Data.
Brent crude for August delivery dipped 3.18 dollars to close at 38.55 dollars a barrel on the London ICE Futures Exchange.
The moves came after coronavirus cases increased in some U.S. states that are reopening up from lockdowns.
More than 2 million confirmed COVID-19 cases have been reported in the United States, with over 113,000 deaths as of Thursday afternoon, according to the Center for Systems Science and Engineering at Johns Hopkins University.
Oil prices were also dragged as data showed a surprise build in U.S. inventories.
U.S. crude oil inventories increased by 5.7 million barrels during the week ending June 5, the U.S. Energy Information Administration said Wednesday.