At least 400 people in Madaya are in need of urgent evacuation from the Syrian town for medical treatment, the United Nations said.
"Around 400 are in need of being evacuated for life-saving medical attention... They are in grave peril of losing their lives," AFP quoted UN aid chief Stephen O'Brien as saying after a security council meeting.
US Ambassador to the United Nations Samantha Power also said, "Over 400 people are on the brink of death in need of immediate medical evacuation" from Madaya.
The UN said it has discussed the evacuation with the Syrian government and hopes the Bashar al-Assad administration will grant permission on Tuesday. Permission 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" is also needed, O'Brien said.
After sending an aid convoy to the besieged town on Monday, the UN confirmed that hundreds were starving to death in Madaya. As many as 44 trucks of the UN, the International Committee of the Red Cross and the Syrian Red Crescent reached the Syrian town with medical and food supplies, blankets, baby formula and soap on 11 January.
"We have seen with our own eyes severely malnourished children. I am sure there also malnourished older people and it is true they are malnourished, and so there is starvation," Yacoub El Hillo, the UN resident and humanitarian coordinator in Syria, told Reuters.
However, Bashar Jaafari -- the permanent representative of Syria to the UN -- said the reports of starvation in Madaya were not true. He added that the "terrorists inside" the city were stealing the supplies, AFP reported.
The six-month-long siege by government forces and Hezbollah militants has deprived over 40,000 people of medical and food supplies. Several reports had earlier indicated that people in the town were on the verge of starvation.
The medical humanitarian organisation MÃ©decins Sans FrontiÃ¨res (MSF) has recorded 28 deaths due to starvation since 1 December.
Britain and France have asked the Assad government to end the siege for the sake of the people of Syria.
"Starving civilians is an inhuman tactic used by the Assad regime and their allies... All sieges must be lifted to save civilian lives and to bring Syria closer to peace," Matthew Rycroft, British Ambassador to the UN, said in a statement.
"The intra-Syrian negotiations will not resume unless there is an improvement of the civilians' plight," French UN Ambassador Francois Delattre said. The Syrian government and the opposition is reportedly scheduled to meet on 25 January in Geneva for peace talks.