A fiery explosion rocked a Russian fuel depot near the border around dawn Friday, and Moscow said Ukraine had attacked the facility, but Kyiv denied any involvement. There was no independent confirmation of details about the incident.

Russian Defense Ministry spokesman Igor Konashenkov said two Ukrainian Mi-24 helicopters had entered Russian airspace "at an extremely low altitude" and attacked the civilian oil storage facility on the outskirts of the city of Belgorod.

He said the facility was supplying petroleum "to civilian transport only. The oil base has nothing to do with Russian armed forces."

Regional Gov. Vyacheslav Gladkov said two workers at the depot were injured, he said. But Russian media cited a statement from state oil company Rosneft that denied anyone was hurt.

More than 300 firefighters battled the blaze, using a helicopter and a special firefighting train, the Belgorod mayor's office said. Gladkov said he met with residents who were moved from their homes to a nearby sports facility. He also posted photos of craters and metal fragments in a rural area where he said explosions had damaged a power line and broken a window.

It would not be the first attack reported inside Russia since the war began Feb. 24, although there has been nothing as dramatic.

Oleksiy Danilov, secretary of Ukraine's national security council, denied Ukraine was responsible.

"For some reason, they say that we did it, but in fact this does not correspond with reality," he said on Ukrainian television.

Earlier, presidential adviser Oleksiy Arestovich said: "We are carrying out defensive operations on our territory. Russian authorities bear responsibility for everything that happens at Russian territory."

Russian authorities "must figure out what's going on in Belgorod," he said. "Maybe someone smoked in the wrong place. Maybe there was something else. Maybe Russian troops are sabotaging orders and don't want to enter Ukrainian territory by available means."

Any airborne attack inside Russia would likely require skillful flying to avoid its air defenses.

The explosion drew a muted response from the Kremlin, with spokesman Dmitry Peskov saying it was not helpful for talks with Ukraine.

On Russian social media, some users expressed surprise that Ukraine was still capable of mounting such an attack or getting past Russian air defenses. Russia's daily video briefings from the Defense Ministry often stress the number of Ukrainian planes and helicopters shot down or destroyed.

Belgorod is about 25 kilometers (16 miles) from the border and is roughly opposite Kharkiv, Ukraine's second-largest city that which has been under Russian bombardment since the early stages of the war.

Earlier incidents in the Belgorod region had caused alarm locally but had little wider resonance in the context of the war, which Russia portrays as a "special military operation" with little effect on the lives of ordinary citizens.

On the first day of the war, three people were reported injured from shelling in Belgorod, although there was no independent confirmation. A statement from Russia's state Investigative Committee said two adults and one child were injured, and an attempted murder probe was launched.

Another criminal investigation by the committee was opened March 1 after a report that two Ukrainian missiles from an Uragan launcher had landed in a rural area. That report also was not independently confirmed.

Gladkov said last week that a shell fired from Ukraine had exploded in a village in the Belgorod region in an incident in which the Russian Orthodox Church said had killed a military chaplain. A similar incident was reported to have damaged houses. There was no independent confirmation of those reports.

Other explosions March 29 were due to what Gladkov said he had heard was a fire at a munitions store in the border village of Krasny Oktyabr, citing "unverified information." Ukraine was not blamed for the incident and Gladkov said he was awaiting official comment from the Defense Ministry, although none followed and the cause of the fire remained unclear.

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