Russian authorities have urged foreigners to leave Kyiv before the launch of a "series of systematic strikes" against military targets in Ukraine's capital.
Russia's foreign ministry said the strikes were a response to what the Kremlin says was a deliberate drone strike on a student dorm in the Russian-controlled Luhansk region of eastern Ukraine.
Ukraine's military denied the Russian accusations and said it had struck an elite drone command unit in the area.
A Ukrainian attack on a residential building in the Russian-controlled town of Starobilsk in the Luhansk region of eastern Ukraine left more than 20 people dead, local authorities said.
Russian authorities said at least 18 students from a teacher training college were killed.
A total of 48 people were reported injured.
The Ukrainian military stated that the target had been a Russian military unit specialising in drone attacks against Ukraine.
"Under these circumstances, the armed forces of the Russian Federation are launching a series of systematic strikes against Ukrainian military-industrial complex enterprises in Kyiv," the Russian ministry said in a statement.
The strikes will include specific sites involved in the design and manufacture of drones as well as decision-making centres and command posts, it said.
In Kyiv, rescuers worked on Monday to deal with earlier Russian strikes on the Ukrainian capital on Sunday, which local authorities said had killed two people and injured 91.
Russia fired an Oreshnik hypersonic missile near Kyiv - its third use of the nuclear-capable weapon in the more than four-year-old war.
About 300 sites across Kyiv were damaged, Ukrainian President Volodymyr Zelenskiy said.
One of the sites was a newly opened museum commemorating the 1986 Chernobyl nuclear disaster.
More than 70 foreign diplomats paid their respects to the victims of the strikes in Kyiv, visiting a heavily damaged neighbourhood in Lukyanivka on Monday.
France's ambassador to Ukraine, Gael Veyssiere, noted that ordinary people had returned to work on Monday and were going about their daily lives.
"It's a way to demonstrate resilience and I think it's extremely important that we, around the world, we would support that," Veyssiere told Reuters.
Meanwhile, Ukraine continued its own attacks against Russian infrastructure and industrial assets.
In Russia's Belgorod region, one man was killed and another injured in a missile and drone attack that also cut power and water supplies, local authorities said on Telegram.
Four people, including two teenagers, were killed in the Russian-controlled eastern Ukrainian town of Horlivka, its mayor Ivan Prikhodko said on Monday on Telegram, blaming a Ukrainian attack.
Reuters could not independently verify the reports.
Russian and Ukrainian forces deny deliberately targeting civilians since Russia invaded Ukraine in February 2022.
with DPA
