The Syrian government has agreed to allow aid into the besieged rebel-held village of Madaya amid reports of residents starving to death.
Human rights activists had warned up to 40,000 civilians were slowly starving to death in the Syrian town of Madaya, after seven months under a punishing siege by Syrian government forces and Hezbollah militias.
The United Nations humanitarian co-ordinator said it was planning to deliver humanitarian assistance "in the coming days".
The UN said it also had government permission for access to Kefraya and Foah in the north but, unlike Madaya, these are besieged by rebel forces.
Up to 4.5 million people in Syria live in hard-to-reach areas, including nearly 400,000 people in 15 besieged locations who do not have access to the life-saving aid they urgently need.
Many of the people in Madaya, encircled by landmines and Lebanese Hezbollah militia forces, have been reduced to eating grass and other wild plants, insects and even cats.
Medical charity Medecins Sans Frontieres believed thousands of civilians were at risk of starvation in the town.
Civilians in Madaya, near the Lebanese border, said people were beginning to starve to death and children were severely malnourished after weeks with no adequate food.
Speaking from inside Madaya, a doctor working with the Syrian American Medical Society said deaths had been occurring almost daily due to a lack of food.
Khaled, who would only be identified by his first name, told the ABC that babies were being given salted water because there was no milk.
Video purportedly filmed inside the town and sent to the ABC showed a severely malnourished baby and small boy.
The skinny child was heard saying he had not eaten properly for seven days.
"We want doctors to help, the UN should get involved to see how people are starving here, we must get some help, food with in the next 24 hours," Dr Khaled said.
"Every day [that] passes by it costs us lives of people. Please, the international community must act fast, please act fast to save the lives of the people here."
A senior official with Medecins San Frontiers confirmed to the ABC that they believed people in Madaya were already dying of starvation and that if the siege was not lifted soon, they expected more deaths.
"We are very worried about recording more deaths due to malnutrition or lack of access to food," the official said, speaking on anonymity because they worked inside besieged parts of Syria.