“This is the very wrong time to turn our back on civilians,” he told journalists in Geneva, highlighting that aid projects in Syria are now less than eight per cent funded.

Egeland, who had earlier attended a scheduled meeting of the UN-supported humanitarian task force on Syria, said that more than half a million men, women and children had been displaced in the last three months in and around Idlib, from Eastern Ghouta, and from the district of Afrin in northern Aleppo.

He described mass evacuations of civilians as “desperate measures in desperate times” adding that they had played their part in ending battles in urban areas in Syria.

But they have also contributed to a desperate humanitarian situation.

In Idlib Province alone, some 1.5 million people were now displaced in various locations, making it “the biggest refugee camp on earth in many ways,” said Egeland, who is the Senior Adviser to UN Special Envoy for Syria Staffan de Mistura.

Egeland also provided details about the destruction of Raqqa city, once the stronghold of Islamic State of Iraq and the Levant (ISIL) extremists, saying that it was even worse than in Aleppo and Homs, two other once-vibrant Syrian cities that have seen massive destruction over the course of the seven-year conflict.

On the final push for Eastern Ghouta, just outside the Syrian capital, Egeland said that there had been “no recent reports of fighting and air raids” and “hopefully the battle is over now in the heavily populated areas.”

Until recently more than 400,000 people had been besieged for years in parts of Eastern Ghouta.

The area has been subject to a Government-backed offensive launched in mid-February and now only 130,000 people still live there, Mr. Egeland said.

Of that number, around 80,000 have gone to shelters in Government-held areas of Rural Damascus and one-third have left voluntarily – an important indicator of freedom of movement, the humanitarian official added.