Sixty-one hospitals in Ukraine are not operational because of attacks by Russian forces, Health Minister Viktor Lyashko said on Tuesday. Ukraine's parliament on Thursday appointed Lyashko as the new health minister.

"Terrorists from the aggressor country have put 61 hospitals out of action," he said on television, adding that the authorities were unable to deliver critical medical supplies to front-line communities because of a lack of "humanitarian corridors."

Attacks on hospitals, ambulances and other health care facilities in Ukraine have increased rapidly in recent days and the country is running short of vital medical supplies, the World Health Organization (WHO) said on Tuesday.

The U.N. agency confirmed on Monday that at least nine people had died in 16 attacks on health care facilities.

The supply of oxygen, children's vaccines, especially against polio amid an outbreak, and mental health expertise are among the WHO's top priorities for the region.

In a separate statement, the European Centre for Disease Prevention and Control (ECDC) said countries neighbouring Ukraine which are hosting Ukrainian refugees should include them in their vaccine programmes against a range of diseases.