The UN Security Council on Monday discussed the besieged towns of Syria after reports emerged that tens of thousands of civilians have been trapped for months without supplies and are starving to death.
The meeting was called by New Zealand, Spain and France in response to the reports of people dying in the town of Madaya and elsewhere due to a lack of food and medical attention.
More than 20,000 children in Madaya are at risk of further hunger and starvation, the United Nations Children's Fund said on Friday.
Aid convoys entered the besieged Syrian town of Madaya near the Lebanese border on Monday as part of an agreement between warring sides.
Vehicles from the International Committee of the Red Cross arrived in Madaya from Damascus, where thousands of civilians are starving to death because of a siege by Syrian regime forces.
The Red Cross also announced on its Twitter account that aid vehicles are also leaving for Foua and Kefraya which are surrounded by anti-regime fighters in Idlib Province.
Trucks were to simultaneously enter Madaya, which has been blockaded for months by Syrian regime leader Bashar al Assad's forces and where aid agencies have warned of widespread starvation, and al Foua and Kefraya in Idlib Province, which are encircled by opposition fighters.
US Ambassador Samantha Power also had strong words about Madaya, slamming the "grotesque starve-or-surrender tactics the Syrian regime is using right now against its own people."
"Look at the haunting pictures of civilians, including children, even babies, in Madaya," she told the General Assembly.
"These are just the pictures we see. There are hundreds of thousands of people being deliberately besieged, deliberately starved, right now. And these images, they remind us of World War Two."
Power was speaking at a special session of the 193-nation U.N. General Assembly on the 70th anniversary of the assembly's first meeting in London.
British Ambassador Matthew Rycroft said "starving civilians is an inhuman tactic used by the (President Bashar) al-Assad regime and their allies."
"All sieges must be lifted to save civilian lives and to bring Syria closer to peace," he said in a statement, adding that there were 850 infants in urgent need of milk in Madaya.
Syrian regime representative Bashar Ja'afari told reporters the Assad regime was committed to "cooperate fully" on aid delivery but said much of what was said about Madaya was "based on false information." He labeled pictures of starving people as "fabrications."
"There is no shortage of humanitarian assistance in Madaya," he said, adding that some aid has been "looted by armed terrorist groups."
UN humanitarian chief Stephen O'Brien, however, told reporters the reports of people starving to death in Madaya were "wholly credible." He added that some 400 people there were in dire need of medical evacuation.
The Syrian conflict has been raging for nearly five years and has claimed more than a quarter million lives.
A UN Security Council resolution adopted on Dec. 18 set out a road map for peace talks and called on the parties to allow aid workers unhindered access throughout Syria, particularly in besieged and hard-to-reach areas.
French Ambassador Francois Delattre said there could be "no credible political process without progress on the humanitarian front."
The blockade of Madaya has become a focal issue for Syrian opposition leaders, who told a UN envoy last week they would not take part in talks with the regime, slated for later this month, until it and other sieges are lifted.