MOSCOW/KYIV: A Ukrainian drone sparked a fire at an oil refinery in southern Russia and shelling hit a Russian town close to the border for the third time in a week, damaging buildings and setting vehicles ablaze, Russian officials said on Wednesday.

A day after Russia accused Ukraine of sending drones to attack buildings in Moscow, the governor of Russia's Krasnodar region said a drone was the likely cause of a fire that broke out at the Afipsky oil refinery.

The fire was soon extinguished and there were no casualties, Governor Veniamin Kondratyev said on the Telegram messaging app. The Afipsky refinery is not far from the Black Sea port of Novorossiisk, near another refinery that has been attacked several times this month.

There was no immediate information on who launched the drone but Moscow has accused Kyiv of increased attacks inside Russia in recent weeks, while Russia has repeatedly pounded Ukrainian cities with drones and missiles.

The skies over Ukraine were relatively quiet on Tuesday night, with no major air raids reported. Russian drone attacks killed one person and wounded four in Kyiv on Tuesday, according to Ukrainian officials.

The attacks inside Russia come as Ukraine prepares a counter-offensive to drive Russian forces out of territory occupied since Moscow launched its full-scale invasion of Ukraine in February 2022.

A Ukrainian artillery strike wounded at least one person in the Russian town of Shebekino, about 7 km (4.5 miles) north of the border with Ukraine's Kharkiv region, regional Governor Vyacheslav Gladkov said on the Telegram messaging app.

Ukraine almost never publicly claims responsibility for attacks in Russia or on Russian-controlled territory in Ukraine.

DRONE WAR

Ukrainian drones struck wealthy districts of Moscow on Tuesday, Russia said in what one politician called the most dangerous attack on the capital since World War Two, while Kyiv was also hit from the air for the third time in 24 hours.

Aerial strikes by both sides have intensified amid a stalemate on the ground with Russian forces entrenched along an extended line in Ukraine's east and south.

The Russian defence ministry said eight drones sent to Moscow by Ukraine and targeting civilians were shot down or diverted with electronic jammers, though Baza, a Telegram channel with links to the security services, said there were more than 25.

Mykhailo Podolyak, a Ukrainian presidential aide, denied Kyiv was directly involved but said "we are pleased to watch events" and forecast more such strikes.

Two people were injured while some apartment blocks were briefly evacuated, according to Moscow's mayor. Residents said they heard loud bangs followed by the smell of petrol. Some filmed a drone being shot down and a plume of smoke.

The drones targeted some of Moscow's most prestigious districts including where Russian President Vladimir Putin and other members of the elite have homes.

Putin said Ukraine's biggest drone strike on Moscow was an attempt to frighten and provoke Russia, and that air defences around the capital would be strengthened.

Civilian targets in Kyiv and other Ukrainian cities have since the earliest days of the war been struck repeatedly by Russian drones and missiles.

But Tuesday marked only the second time Moscow had come under direct fire.

In Washington, the White House said it was gathering information on the reports of drones striking in Moscow.

"We do not support attacks inside of Russia. That's it. Period," White House press secretary Karine Jean-Pierre said at a briefing.

Washington is a major supplier of weaponry to Ukraine on the condition it uses it to defend itself and to retake Ukrainian territory occupied by Russian forces.

Russia's ambassador to the United States accused Washington of encouraging "terrorists" in Kyiv by publicly ignoring the drone attack.

NUCLEAR THREAT

One of the southern places Russian forces have controlled since just after the beginning of the invasion is the Zaporizhzhia nuclear power plant, and on Tuesday the chief of the U.N. nuclear watchdog asked Ukraine and Russia to respect five principles to safeguard it. Neither Ukraine nor Russia have committed to respect the principles.

International Atomic Energy Agency (IAEA) chief Rafael Grossi has been trying for months to secure an agreement to reduce the risk of a nuclear accident from military activity like shelling at Zaporizhzhia, Europe's biggest nuclear power plant.

In a briefing to the U.N. Security Council, Grossi said the principles included that there should be no attack on or from the plant and that it not be used as a base for heavy weapons and other military equipment. He called for off-site power to the plant to remain available and secure.

(Reporting by David Ljunggren, Guy Faulconbridge, Max Hunder, Olena Harmash, Pavel Polityuk, Valentyn Ogirenko, Gleb Garanich, Lidia Kelly, Trevor Hunnicutt and Steve Holland; Writing by Stephen Coates; Editing by Robert Birsel)