Ukrainian officials said a Russian missile slammed into a cafe and grocery store in a village in northeastern Ukraine on Thursday, killing 51 people during a gathering to mourn a fallen Ukrainian soldier.

Ukrainian President Volodymyr Zelenskiy said the incident was a deliberate attack on civilians and "no blind strike". Moscow did not immediately comment on the events in Hroza. Russia denies deliberately targeting civilians.

Large piles of bricks, shattered metal and building materials remained where the cafe and shop were hit early in the afternoon in Hroza village in Kharkiv region.

The attack was the deadliest in Kharkiv region since Russia's war began more than 19 months ago, a regional official told public broadcaster Suspilne. It also appeared to be one of the biggest civilian death tolls in any single Russian strike.

Regional police told national television the death toll stood at 51, with six injured and three missing. Some of them were mourners gathering in the cafe after a service for a fallen soldier from the village.

"A deliberate missile strike on a village in Kharkiv region on an ordinary store and cafe," Zelenskiy said in his nightly video address, delivered while attending a summit of the European Political Community in Spain.

"Russian troops could not have been unaware of where they were hitting. This was no blind strike."

The village was near the town of Kupiansk, recaptured by Ukrainian forces late last year and close to one of the war's front lines.

Zelenskiy said a six-year-old boy was among the dead and regional officials said families had remained in the village despite a war-time order to evacuate. (Reuters)