Humanitarian workers who visited the town with the convoy this month described appalling conditions, including about 400 people identified as requiring urgent medical care. But most of those people have not been evacuated for medical treatment, and some of them are among the nine people who have since died from severe shortages of food and a lack of medical care, Abdullah said.
The issue of hundreds of thousands of people in multiple areas across Syria who are living under sieges imposed by the Government and rebel fighters appears to be a major sticking point in peace talks scheduled to start overnight in Geneva.
After a meeting in Saudi Arabia on Wednesday, a key opposition group rejected attending the talks without "genuine improvements on the ground", a reference to lifting government sieges.
The siege of Madaya has raised more questions about the UN humanitarian relief effort in the Syrian conflict, which has left more than 250,000 people dead and displaced millions. Government sieges are more intense and affect more people in Syria than those imposed by the armed opposition.
But opposition activists accuse UN humanitarian officials of acquiescing to Assad's Government, which routinely denies permission to deliver aid to besieged opposition areas.
In a strongly worded statement to the UN Security Council on Thursday, the UN's humanitarian chief, Stephen O'Brien, called out warring parties to the conflict over the sieges.
He expressed particular concern for Madaya, which he said represented only the "tip of the iceberg" in terms of the extent of suffering in Syria caused by the sieges.
He also said the Government has failed to respond to roughly 75 per cent of UN requests to deliver aid to besieged areas.
As Assad's Government continues what opponents describe as a long-running practice of attempting to starve disloyal populations into submission, UN officials are increasingly questioning the world body's strategy of providing aid.
"I think it's really time to change our approach. We've been soft in trying to negotiate deals over the last five years, and it just hasn't been working," said one UN official, speaking on the condition of anonymity because of a lack of authorisation to discuss the issue.
For people in Madaya, the failure to end the siege has led to growing desperation.
Images on social media purporting to show the town's suffering, including bone-thin boys and sickly elderly people, have brought international attention to the issue. About two dozen people starved to death before the convoy arrived this month, aid workers and residents said.
Now, residents say they are rationing the recently received food aid, which is supposed to last a month from the date of delivery, as prices for edible goods start to soar again. After dropping temporarily, the price of two pounds of rice is more than US$100 ($153), residents say. Meat, fresh fruits and vegetables are not available.
"All the women here are suffering from anaemia," said Umm Omar, 40, who runs a community group for women in the town.
"There are so many complications for women who are giving birth. We don't have the right doctors to deal with these issues," said Umm Omar, using a traditional nickname. She asked that her full name not be used because she feared retaliation from the Syrian Government.
A lack of electricity and diminishing supplies of firewood have raised Jinan's concerns for the health of her 12-year-old son, Jamil, and 9-year-old daughter, Rama. They can't heat their home, and they are already rationing the food brought in this month, with each of them eating one meal a day, she said.
"This food helps, but it's not enough to last and it's not nutritious. We need meat and vegetables," said Jinan, who spoke on the condition that only her first name be used because of safety concerns.
"I try to eat grass to get something green like a salad," she said. "But I am afraid to let my children eat it because it could be harmful for them."
The UN-backed agreement that allowed the convoys into Madaya included similar aid delivered to two rebel-besieged villages in a different province where residents also face deteriorating humanitarian conditions.
The UN Office for the Co-ordination of Humanitarian Affairs requested permission last week to conduct a nutritional assessment in Madaya, but the Syrian Government has not responded, said Linda Tom, a spokeswoman for the UN agency.
However, Elizabeth Hoff, the World Health Organisation representative in Damascus, said the Government recently approved a request to send mobile medical clinics to Madaya.
But residents said that only a lifting of the siege would end their suffering.
"Our bodies are weak right now, and any kind of illness could be a killer," Abdullah said. "We need this to end."
