Russia said Wednesday it had shot down two drones aimed at President Vladimir Putin's Kremlin residence in what it called a Ukrainian "terrorist" assassination attempt.
Kyiv said it had "nothing to do" with the alleged attack and suggested it was "staged" by Moscow.
Russia announced the incident after a series of extraordinary sabotage attacks in the run-up to celebrations for the nation's most important holiday on May 9, marking the Soviet victory over the Nazis.
"Today at night, the Kyiv regime attempted to strike the Kremlin residence of the President of the Russian Federation with unmanned aerial vehicles," the Kremlin said.
"Two unmanned vehicles were aimed at the Kremlin... the devices were put out of action," a Kremlin statement said.
The operation was described as "a planned terrorist act and an attempt on the life of the President of the Russian Federation."
Moscow said Putin was not hurt and there were no casualties.
Kremlin spokesman Dmitry Peskov said Putin was working at his residence near Moscow on Wednesday and would still take part in a scheduled World War II Victory Day parade on Red Square next week as planned.
Kyiv said it did not target the Kremlin.
"Ukraine has nothing to do with drone attacks on the Kremlin," presidential spokesman Mikhaylo Podolyak said.
"Such staged reports by Russia should be considered solely as an attempt to prepare an information background for a large-scale terrorist attack on Ukraine," Podolyak said.
On Red Square, AFP saw nothing unusual with people out for a stroll and no strengthened police presence. Banners have been set up ahead of the May 9 parade.
Moscow has vowed that the parade -- central to Putin's rule -- will go on as normal.
Victory day plans
The alleged thwarted operation comes on the heels of a series of incidents -- including sabotage attacks on trains -- ahead of the popular WWII victory celebrations.
The last five days have seen two trains derailed by explosions, oil depot fires near and in Crimea, and power lines blown up near Saint Petersburg.
Officials in Russia said they were dealing with a major fire at a fuel depot close to the bridge to Russian-annexed Crime in the night between Tuesday and Wednesday.
A source in the emergency services was quoted by TASS news agency as saying that the fire had been caused by a drone.
They hit as Moscow gears up for the May 9 celebrations.
A range of cities near the Ukraine border, but also some more distant, have cancelled traditional parades.
But Moscow has vowed that the central Red Square parade will go ahead as normal.
Kremlin spokesman Dmitry Peskov said the parade in Moscow was going ahead as expected with "no changes to the plans", according to news agencies.
Moscow's mayor announced a ban on unauthorised drone flights over the Russian capital.
In a statement, mayor Sergei Sobyanin said drone flights would be prohibited unless a special permit had been obtained from "government authorities".
The Kremlin news came as Ukraine prepared for a fresh offensive aimed at repelling Russian forces from the territory they currently hold in the east and south.
Counter-offensive preparations
In possible signs that preparations are being stepped up, the frontline city of Kherson in southern Ukraine announced a long curfew for residents and sabotage acts behind Russian lines intensified.
Kherson, which was re-taken by Ukrainian troops in November, will be under curfew from Friday evening until Monday morning.
Regional officials said this was "for law enforcement officers to do their job", but similar long curfews have also been used in the past for troop and arms movements.
"During these 58 hours, it is forbidden to move on the streets of the city. The city will also be closed for entry and exit," the head of Kherson's regional military administration, Oleksandr Prokudin, said on Telegram.
He advised residents to stock up on food and medicine and said people could go for short walks near their houses or visit shops and carry identity documents with them at all times.
Kherson was captured by Russian troops last year in the first days of the invasion and remained under Russian occupation until November 2022.
After a sustained campaign of sabotage attacks behind Russian lines, Russian forces withdrew from the city.
They crossed to the eastern side of the Dnipro River which now delineates part of the front line in southern Ukraine.
Meanwhile NATO's newest member Finland welcomed Ukrainian President Volodymyr Zelensky on a surprise visit to take part in a summit with the leaders of the five Nordic nations which have been key providers of military aid.
"In order to be in NATO and support alliances to gain support, fundamental diplomatic work must be done. Ukraine is doing it today," Daria Zarivna, Ukraine's presidential communications adviser, wrote on Telegram.