Ukraine struck one of Russia's largest oil refineries on May 20, Ukraine's General Staff said — marking the second reported hit on the site within a week.

Axar.az reports, citing Kyiv Independent, according to the General Staff, an AVT-6 oil refining unit was hit, leading to a subsequent fire at the Lukoil-Nizhegorodorgsintez refinery near the town of Kstovo in Russia's Nizhny Novgorod Oblast.

Residents of the city of Kstovo in Nizhny Novgorod Oblast reported seeing drones approaching the refinery in the early morning, followed by reports of explosions in the area.

The attack marks the second time the Lukoil-Nizhegorodnefteorgsintez oil refinery has been struck in the past week, with a fire previously reported following a Ukrainian attack on May 18.