'We must all be ashamed', says Syria aid chief

The United Nations' aid chief on Thursday strongly appealed to world powers to revive the ceasefire in Syria and put an end to the "massive human suffering" that has deprived millions of people of food and medicine.

"We must all be ashamed this is happening on our watch," Stephen O'Brien told the Security Council during a meeting on the appalling humanitarian crisis stemming from the five-year war.

The meeting came a day after UN peace envoy Staffan de Mistura told the council that the ceasefire, which had allowed aid convoys to reach starving civilians in besieged towns, was hanging by a thread.

Echoing De Mistura's call, O'Brien appealed for action to salvage the ceasefire that went into force on February 27 and paved the way for peace talks.

"You must not squander the opportunity presented by talks in Geneva and by the cessation of hostilities to put an end to the massive human suffering in Syria," said the UN under-secretary general for humanitarian affairs.

"The world and the people of Syria need this. They need your action."

O'Brien reported an increase in violence in recent weeks in Aleppo, Homs, Idlib, Lattakia and rural Damascus.

He said Syrian forces on Thursday morning had restarted air bombings in Daraa governorate for the first time since the start of the ceasefire.

As the fighting again intensifies, the United Nations is waiting for approval from the Syrian government to deliver critically needed aid to 35 towns, including rebel-held Darayya and Douma.

You must not squander the opportunity presented by talks in Geneva and by the cessation of hostilities to put an end to the massive human suffering in Syria - Stephen O'Brien

Syrian authorities removed medicine and surgical supplies from recent UN convoys to the besieged rebel-held towns of Kafr Batna and Rastan, O'Brien said, condemning "this inhumane practice".

Departing from his written text, O'Brien delivered a stern warning that those responsible for depriving civilians of medical aid would face justice.

"There can never be impunity for this behaviour," he said.

The United Nations estimates that 13.5 million Syrians, including six million children, are in need of humanitarian aid.

Of these, 4.6 million people are in hard-to-reach areas, including close to 500,000 people in towns under siege.

O'Brien warned that without a restored ceasefire, "the situation will only spiral further and further out of control" in the war that has already killed more than 270,000 people and displaced millions.