The World Health Organization has warned that the upcoming winter would be life-threatening for millions of Ukrainians after a series of devastating Russian attacks on the country's energy grid.

Regional Director for Europe at the United Nations Hans Kluge, told reporters during his visit to Kyiv that damage to Ukraine's energy infrastructure caused by numerous missile strikes is already having knock-out effects on the health system and on the people's health.

He said the WHO has recorded more than 700 attacks on Ukraine's health facilities since Russia's invasion began in February.

He said continued attacks on health and energy infrastructure mean hundreds of hospitals and health care facilities are no longer fully operational.