A Russian strike has killed at least four people, including three young children, in a town west of Kharkiv, a Ukrainian official says.

Oleg Synegubov, head of the Kharkiv Regional Military Administration, said two boys, both 1, a two-year-old girl and a 34-year-old man died after a drone hit a house they were staying in.

A 35-year-old pregnant woman and another woman, 76, were injured in the strike on Bohodukhiv, Synegubov said.

Tuesday night's attack on Bohodukhiv comes as Moscow renews strikes after a week-long pause US President Donald Trump had asked Russian President Vladimir Putin to observe as a fierce cold swept Ukraine.

Russian forces also dropped seven bombs on the city of Slovyansk around 12:00 on Tuesday, Donetsk regional governor Vadym Filashkin said on Telegram. Two people, including an 11-year-old girl, were killed.