MOSCOW (Reuters) - Ukrainian drones hit a Russian oil refinery in the city of Ryazan overnight, causing a fire and damaging equipment at one of Russia's biggest refineries, four industry sources told Reuters on Friday.

The sources said oil storage at the refinery had been set ablaze. Among damaged equipment were a railway loading rack and a hydrotreater unit used to remove impurities from refined products. Reuters was not immediately able to reach Rosneft, Russia's large state oil company, which owns the refinery.

Russia's Defence Ministry said its air defences had repelled a massive Ukrainian drone attack overnight, intercepting and destroying 121 drones targeting 13 regions, including Moscow. It made no mention of casualties or damage.

It said 20 had targeted the Ryazan region, which is southeast of Moscow.

Ukraine also said it had hit the Ryazan refinery. Andriy Kovalenko, head of Ukraine's centre for countering disinformation, described the refinery as one target, along with the Kremniy plant in Bryansk, which Kyiv says produces microelectronics for Russian weapons systems.

Channels on the Telegram messaging app posted unverified videos of what bloggers described as large blazes in Ryazan. They said an oil storage depot and a power station had been hit.

The industry sources said that the railway loading rack caught fire after the attack.

"A 20,000-tons reservoir is on fire. Adjacent reservoirs were also damaged, the loadings have been suspended," a source said.

Ryazan oil refinery processed 13.1 million metric tons (262,000 barrels per day), or almost 5% of Russia's total refining throughput in 2024.

It produced 2.2 million tons of gasoline, 3.4 million tons of diesel, 4.3 million tons of fuel oil and 1 million of jet fuel, according to a source-based data.

(Reporting by Reuters; Editing by Peter Graff)