By Paul Purcell and Sarah Robson
New Zealand and Spain have prompted an emergency meeting of the United Nations Security Council on the humanitarian situation in the besieged Syrian town of Madaya.
The two non-permanent members of the council called for Tuesday's meeting (NZ time) late last week.
In the interim, the crisis has worsened with Spanish ambassador Roman Oyarzun Marchesi revealing 400 people are in need of evacuation by Tuesday or the situation would be "more dramatic" on Wednesday.
"They need a medical evacuation on an urgent basis tonight," New Zealand permanent representative to the UN Gerard Jacobus van Bohemen said.
"They want permission from the Government of Syria to let those people out."
Mr van Bohemen was unable to elaborate on the nature of their condition.
The high-level talks come as the first UN aid convoys carrying food and medical supplies reached the town, located near the Lebanese border, and confirmed the dire state of affairs.
Thousands of people have been trapped in Madaya, according to reports, which has been besieged by pro-Syrian government forces for months, without supplies while people die from starvation.
The tactic of siege and starvation is "one of the most appalling characteristics of the Syrian conflict," van Bohemen, says.
"It's encouraging that a convoy of humanitarian supplies has arrived in Madaya today, but this is just the start," he said.
"It cannot be just a one-off situation."
"Humanitarian access cannot be held hostage to the politics."
Earlier, the Syrian ambassador Bashar Ja'afari rebuked the accusations of starvation.
The problem, he said, was armed groups taking food from UN convoys and the Red Crescent humanitarian group, putting it in warehouses and selling it at exorbitant prices to desperate civilians.
The UN will be following the situation on an hour-by-hour basis.