Ukrainian drone strikes killed three people in Russia's border region of Belgorod and injured 19 others in an attack on a bus. The Russian Foreign Ministry condemned the attacks.
Regional authorities said on Tuesday a drone strike on a business in a village near the border killed two people.
Another person was killed in an attack on a town outside the region's main city, also called Belgorod.
The bus came under fire in the town of Shebekino, near the Ukrainian border, and all but one of those injured were sent to hospital for treatment.
Moscow has accused Ukraine of staging systematic attacks on buses in different Russian regions.
'Maniacal persistence'
Russian Foreign Ministry spokesperson Maria Zakharova said the latest strike showed Ukraine was directing attacks on public transport "with a maniacal persistence, taking revenge on ordinary people for growing failures at the front."
Russian authorities in parts of eastern Ukraine's Donetsk region under Russian control said five people were injured on Tuesday in what they said was a Ukrainian drone strike on a bus.
Russian authorities also blamed Ukraine for an attack last month on a bus carrying Belarusian children to a holiday site, which killed a woman and injured six children.
Ukraine's military rejected the accusation as false.
