UN official Mark Cutts says this is not the time for people to take their eye off Syria.

In the past three months, nearly one million people have fled advancing Syrian government forces in Idlib province near the border with Turkey. With Ankara refusing to open border crossings and millions of civilians trapped, the United Nations has warned of an impending bloodbath and a "massacre on a scale that has never been seen during this entire war".

Mark Cutts, the UN's deputy regional humanitarian coordinator for Syria, called it a "crisis on a monumental scale".

Women and children are seeking shelter in caves and freezing to death while hospitals, bakeries and schools have been bombed.

Acknowledging that war crimes have been committed by "all sides", Cutts points out that "the majority of the civilian deaths and injuries in the Idlib area have been caused by air strikes and shelling carried out by Syrian government forces and their allies".

"We know this very well and we've been calling on all of them repeatedly", Cutts added.

He urged the international community to work towards a political solution to the humanitarian crisis and called on people around the world to pressure their governments to act.

With the conflict entering its tenth year, Cutts admitted that getting the public's attention has been a challenge.

"There's a lot of fatigue when it comes to Syria because they've seen so many battles and so much displacement … But just at the time when we thought we'd seen the worst of this war, when we thought the war might be coming to an end, what we've seen is one of the worst catastrophes of the entire war". Cutts said.

"This is not the time for people to be taking their eye off Syria," he added.