Crude oil prices were down on Thursday as the weekly increase in US crude oil inventories and gasoline stocks revived worries that the glut of supply in storage will not move on the global oil market.
International benchmark Brent crude was trading at $40.43 per barrel at 0626 GMT for a 3.1% decline after closing Wednesday at $41.73 a barrel.
American benchmark West Texas Intermediate (WTI) was at $38.13 a barrel at the same time for a 3.7% loss after ending the previous day at $39.60 per barrel.
US commercial crude oil inventories rose by 5.7 million barrels for the week ending June 5, according to the Energy Information Administration (EIA), against the market estimate of a decline of 1.7 million barrels.
Gasoline stocks also rose by 0.9 million barrels during that period, much higher than the market expectation of an increase of 71,000 barrels, the EIA figures showed.
Rising crude and gasoline inventories in the US show that demand is still low in the world's biggest oil-consuming country due to coronavirus-related quarantine measures.
Investors are concerned that the glut of oil supply will be difficult to trim in the face of weak consumption, which continues to keep downward pressure on prices.
By Ovunc Kutlu