TOKYO: Oil prices fell for a sixth day in their longest losing streak since February 2020, as a spike in COVID-19 cases worldwide fuelled fears of lower fuel demand while a surprise build in U.S. gasoline inventories and a stronger dollar added to the pressure.

       Brent crude was down $1.11, or 1.6%, at $67.12 a barrel at 0639 GMT, after touching the lowest since May 24 at $67.06 earlier in the session.

       U.S. West Intermediate crude (WTI) fell $1.35, or 2.1%, to $64.11 a barrel after falling to as low as $64.02, also the lowest since May 24.

       WTI has dropped more than 7% while Brent has slumped more than 6% during the six-day losing streak, the longest since a six-day decline for both contracts that ended on Feb. 28, 2020.

       The declines reflect worries over rising coronavirus infections caused by its Delta variant, with virus-related deaths in the United States, the world's largest oil user, spiking over the past month.

       "Crude prices continue to look vulnerable around those mid to late summer support levels - $65 in WTI and $67 in Brent," Craig Erlam, senior market analyst at OANDA Europe, said in a note.

       Slower growth in China, the world's biggest oil importer, caused by new restrictions in response to rising COVID-19 cases and some weakness in U.S. data over the past week have driven the softness in oil prices, Erlam said.

       "A move below $65 in WTI, for example, could see prices drop back into Q2 trading ranges between $57 and $65. This would be quite a drop from the levels we've seen the last couple of months," he added.

       An unexpected rise in U.S. gasoline inventories last week also fanned concerns over slowing demand, given demand for gasoline typically peaks during the northern hemisphere summer.

       Gasoline stockpiles rose by 696,000 barrels to 228.2 million, the Energy Information Administration said on Wednesday, against analysts' expectations for a 1.7 million-barrel drop.

       However, U.S. crude inventories fell 3.2 million barrels last week to 435.5 million, their lowest since January 2020, the EIA said.

       "The U.S. peak summer driving season is ending soon just as the country is set to raise output," said Hiroyuki Kikukawa, general manager of research at Nissan Securities.

       U.S. shale oil output is expected to rise to 8.1 million barrels per day in September, the highest since May 2020, according to the EIA's monthly drilling productivity report.

       "Oil prices will stay under pressure in the short-term from seasonal factors and pandemic fears," Kikukawa said.

       A stronger dollar also weighed on investor sentiment.

       The dollar rose to a nine-month high against its major peers on expectations that the U.S. Federal Reserve will start tapering its huge stimulus this year, making dollar-priced oil more expensive to holders of other currencies. - Reuters