The utilization rate of crude distillation units (CDUs), excluding an impact from scheduled maintenance, fell from 99% a year earlier, but it was much higher than the 68% of industry leader Eneos Holdings.

Cosmo's sales of four key petroleum products -- gasoline, kerosene, diesel and fuel oil A -- rose 11% in the quarter from a year earlier, outperforming the country's fuel demand which fell 11%.

But Japan's third-biggest refiner reported a net loss of 26 billion yen ($244 million) for the quarter, against a profit of 14.78 billion yen a year earlier, as hefty inventory losses due to a slump in oil prices ate into its profit.

Still, it kept its May forecast of a profit of 14.5 billion yen for the financial year to next March.

"Our fuel sales have been exceeding our earlier estimates despite the pandemic, but it is still uncertain if the recovery trend will continue through March as the recent spike in coronavirus cases started to weigh on fuel demand in August," Cosmo Energy Holdings Senior Executive Officer Takayuki Uematsu told a news conference.

Tokyo said on Friday it had confirmed 389 new cases of coronavirus infections, as the daily tally rose above the 300 mark for the first time since Aug. 9.

($1 = 106.7200 yen)

(Reporting by Yuka Obayashi; editing by David Evans)