More than two dozen people have reportedly starved to death in Madaya, crippled by a six-month government siege that has made even bread and water hard to find.
Yesterday, the first trucks of aid in about four months entered the town, delivering desperately needed food and medicine.
But hundreds of residents remain in need of urgent care, and humanitarian organisations were working on their evacuation, according to International Committee of the Red Cross spokesman Pawel Krzysiek.
He said the ICRC, the United Nations and the Syrian Arab Red Crescent were all "working on" the evacuation process.
UN aid chief Stephen O'Brien yesterday called for Syria's government to allow the 400 people to leave the town to receive medical care.
"They are in grave peril of losing their lives," O'Brien told reporters after a UN Security Council meeting.
Permission for safe access must come from "all the parties who govern any of the routes that need to be deployed, either for the ambulances or for any kind of air rescue," said O'Brien.
"There is no comparison in what we saw in Madaya," Sajjad Malik told journalists in Geneva, when asked to compare the devastation in the town to other areas in Syria.
He had travelled to Madaya yesterday along with the UN's aid convoy, and expressed shock at the devastation in the town.
"There are people in Madaya, but no life. What we saw in Madaya should not happen in this century," Malik said. "We want to make sure the siege is lifted and this is not a one- off."
Ambassador Bashar Jaafari said the reports were aimed at "demonising" the regime of President Bashar al-Assad.
