Ukraine struck overnight a Russian oil depot that serves a military airfield in the Russian city of Engels, Ukraine's military said Wednesday.

It reported multiple explosions and a big fire at "Kristal" oil depot, which it said provided fuel to the "Engels-2" military airfield, where Russia's strategic bomber fleet is based.

"The strike of the oil depot creates serious logistical problems for the strategic aviation of the Russian occupiers and significantly reduces their ability to strike at peaceful Ukrainian cities and civilian objects," the Ukrainian military said in a statement via the Telegram messaging app.

Ukraine's presidential adviser Oleksandr Kamyshin said the military used Ukrainian-made long-range capabilities in the attack.

Russian local authorities earlier on Wednesday said the Ukrainian drone attack caused a major fire at an industrial site in the Saratov region.