The medical charity Medecins San Frontiers believes thousands of civilians are at risk of starvation in a Syrian town besieged by the army of President Bashar al-Assad.
Civilians in Madaya, near the Lebanese border, say people are beginning to starve to death and children are severely malnourished after weeks with no adequate food.
The 40,000 residents of the town have been under siege for seven months by Syrian government forces and Hezbollah militias.
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.
The doctor Khaled, who would only be identified by his first name, told the ABC that babies were being given salted water because there is no milk.
Video purportedly filmed inside the town and sent to the ABC shows a severely malnourished baby and small boy.
The skinny child is heard saying he has 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 believe people in Madaya are already dying of starvation and that if the siege is not lifted in the coming weeks, they expect more deaths to be recorded.
"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 work inside besieged parts of Syria.
'Madaya has become like a large prison'
Residents inside Madaya report that people who have tried to break the siege have been shot and killed while trying to escape.
Landmines have also reportedly been laid around the town to prevent people from leaving.
Fighters from the rebel group Ahrar al-Sham are reported to have a presence in Madaya town, but medical activists insist it is a humanitarian situation.
Dr Ammar Ghanem is a member of the Syrian-American Medical Society's board.
He grew up in a town near Madaya and still has family there whom he talks to regularly.
"People who are trying to escape are dying and people who are staying inside are dying," he told the ABC.
Dr Ghanem said he cannot believe this is happening in the 21st century.
"I'm just losing trust in humanity. Madaya has become like a large prison," he said.
Syrian state media has said two towns near Idlib, Kefraya and Fua, have been besieged by anti-government rebels for two years.
The UN says all parties to the four-year conflict in Syria have used siege warfare, in clear breach of international human rights and humanitarian laws.