LVIV: Ukraine accused Russian forces of hitting a psychiatric hospital near the eastern town of Izyum on Friday in what the regional governor called "a brutal attack on civilians".

Oleh Synegubov, governor of the Kharkiv region, said 330 people had been at the hospital at the time, some of them confined to wheelchairs or unable to move, and that 73 had been evacuated.

The number of casualties was being established, he said.

"This is a war crime against civilians, genocide against the Ukrainian nation," Synegubov wrote on the Telegram messaging app.

Reuters was unable immediately to verify the report in an area that has reported heavy fighting since Russian forces invaded Ukraine on Feb. 24. Russia has denied targeting civilians in what it calls a "special operation" to disarm and "de-Nazify" Ukraine.

The reported attack followed the bombardment of a hospital in the southern city of Mariupol in which Ukrainian officials said three people were killed on Wednesday, including a child. Russia has said it will look into the incident but some officials dismissed reports of the attack as "fake news".

Synegubov said separately that Russian forces had shelled residential areas of Kharkiv, the main city in the region, 89 times in one day but that there was no danger to civilians after an institute containing a nuclear laboratory was hit.

An advisor to the Ukrainian Interior Ministry had said on Thursday that Russian planes bombed the institute in Kharkiv that is home to an experimental nuclear reactor.

"There are no threats to the civilian population yet," Synegubov said in a video address.

All Ukrainian nuclear power stations are operating stably but staff in the Zaporizhzhia plant are facing "psychological pressure" at work following its capture by Russian forces, the Ukrainian state nuclear company Energoatom said.

Radiation levels at all plants had not changed, it said.