Guterres said in a statement the board would look at "a series of incidents that have occurred in northwest Syria" since the establishment of the so-called "Idlib de-escalation zone" in September last year by Russia and Turkey.

The committee is not a "criminal investigation" but aimed to "establish the facts for the secretary general," his spokesman Stephane Dujarric said.

The board, headed by Nigerian General Chikadibia Obiakor, will start its work on September 30 but no deadline was given for it to submit its findings.

Several dozen medical facilities with links to the UN have been damaged or destroyed by bombs this year. Russian has denied deliberately targeting civilian installations.

Human Rights Watch urged the new board to "work quickly to attribute attacks on medical facilities and other humanitarian sites in Syria to the forces who committed them" and called on Guterres to publish the findings.

Ten members of the UN Security Council called on Guterres in July to establish an investigative body, angering Russia, diplomatic sources said.

The British ambassador to the UN, Karen Pierce, hailed the establishment of the investigative committee.

"Developments in Hama and Idlib governorates in northwest Syria show a repeat of the military tactics deployed by Syrian forces in the taking of Aleppo city and eastern Ghouta," she warned, adding her support to a resolution being thrashed out since August for a ceasefire in the northwest.

Diplomatic sources said that while Russia is taking part in the discussions on a ceasefire resolution, it deems such a move unnecessary since a ceasefire was declared last year by Moscow and Damascus.

Russia is also seeking to insert clauses in the text excluding "anti-terrorist" operations from any ceasefire deal, something western countries oppose, the same sources said.