Both benchmarks were on track to end the session at their weakest in more than a year.
"It's still all about the virus here," said Bob Yawger, director of energy futures at Mizuho in New York. "It's going to be hard for risk assets to gather momentum." Prices briefly turned positive after the US government reported a drop in gasoline inventories last week. Crude stocks grew by 452,000 barrels to 443.3 million barrels, the Energy Information Administration said, which was less than the 2-million-barrel rise analysts had expected.