The militant-run bastion of Idlib, the last major opposition stronghold in Syria, has faced more than three months of air strikes by the Damascus government and its allies, including Russia.

UN human rights chief Michelle Bachelet has said that the repeated targeting of civilian facilities indicates such sites are being intentionally hit.

The UN's Syria humanitarian chief, Panos Moumtzis, told reporters this week that over the last 100 days his office had confirmed air strikes on "39 health facilities, 50 schools, water points, markets, bakeries (and) multiple civilian neighbourhoods."

But Russia's envoy to the UN in Geneva, Gennady Gatilov, also an ex-deputy foreign minister, said the UN's civilian site tracking in Idlib was based on "false data".

He said that Moscow ensures its military personnel check each alleged strike on civilian targets but find that the details provided by "the UN humanitarian agencies are false".

"They say the particular date a school or a hospital was destroyed in a particular region. They give coordinates.

"Our people start to double check this and they find that there is no hospital with such coordinates, there is no school with such coordinates and the day which is mentioned by the UN humanitarian agencies, on this day, the Russian air force did not act at all," Gatilov said.

He urged the UN to "double-check this information they receive from the NGOs. They don't do this, I don't know why."

The United Nations has warned that fresh fighting in Idlib, which resumed this week after a short-lived ceasefire, had triggered "total panic" in the northwestern area.

Eliminated or prosecuted

Concern is rising that Syrian President Bashar al-Assad's forces will launch a full offensive to flush out Hayat Tahrir al-Sham (HTS), a militant group led by Syria's former Al-Qaeda affiliate, which has controlled most of Idlib since January.

The UN warns that such an operation would cause a humanitarian catastrophe, with the Idlib's three million residents having no where left to run.

Gatilov said Turkey could help ease civilian suffering in Idlib by delivering on its promise to separate "terrorists" from civilians in the region.

"One thing should be understood very clear, the fight against terrorism should never stop," he added.

"All these terrorists should be either eliminated or prosecuted."

Gatilov voiced optimism that UN-led political talks on resolving the conflict would resume by the end of the year.