WHO Emergencies Director Mike Ryan, on an unannounced visit together with WHO chief Tedros Adhanom Ghebreyesus, told a news conference it was the explicit responsibility of warring parties to avoid attacking health facilities, yet the WHO had already documented 200 attacks on hospitals and clinics in the country.
"Intentional attacks on healthcare facilities are a breach of international humanitarian law and as such - based on investigation and attribution of the attack - represent war crimes in any situation," Ryan said.
"We continue to document and bear witness to these attacks ... and we trust that the UN system and the International Criminal Court and others will take the necessary investigations in order to assess the criminal intent behind these attacks."
Russia has denied previous accusations by Ukraine and Western nations of possible war crimes and has also denied targeting civilians in the war.
Ryan said the 200 cases did not represent the totality of attacks on Ukrainian medical facilities, only those the WHO had verified. Kyiv has said there have been around 400 such attacks since Russia invaded Ukraine on February 24.
President Volodymyr Zelenskiy said on Thursday that Russian troops had destroyed or damaged nearly 400 healthcare institutions in Ukraine.
Tedros told the same news conference: "My message to all the people of Ukraine is this: 'WHO stands by you' ... We continue to call on the Russian Federation to stop this war."
WHO member states will on Tuesday consider a resolution against Russia that includes the possible closure of a major regional office in Moscow, a document obtained by Reuters showed last Thursday.
The draft resolution stops short of harsher sanctions such as suspending Russia from the UN global health agency's board, as well as a temporary freeze of its voting rights, three diplomatic and political sources said.
The draft, prepared largely by EU diplomats and submitted to the WHO's regional office for Europe this week, follows a request by Ukraine signed by at least 38 other members including Turkey, France and Germany.
Moscow calls its actions since February 24 a "special military operation" to disarm Ukraine and rid it of what it calls anti-Russian nationalism fomented by the West. Ukraine and the West say Russia launched an unprovoked war of aggression.
AAP With The Project