Syrian opposition groups and international relief organisations are warning of the risk of mass starvation across the country, especially in the besieged Damascus suburbs where a gas attack killed hundreds last month.
With the world's attention focused on the regime's chemical weapons, activists said six people - including an 18-month-old girl - have died for lack of food in one of the stricken suburbs in recent weeks.
Save the Children said in an appeal on Monday that more than four million Syrians, more than half of them children, do not have enough to eat. Food shortages have been compounded by an explosion in prices.
"The world has stood and watched as the children of Syria have been shot, shelled and traumatised by the horror of war," said Roger Hearn, Save the Children's regional director for the Middle East. "The conflict has already left thousands of children dead, and is now threatening their means of staying alive."
Thousands of people are believed trapped in suburbs east and west of the capital that have been held for months by rebels fighting to topple President Bashar al-Assad. Regime troops are besieging the areas and residents say food is increasingly hard to find. Rebels say they are trying to break the blockade.
The suburbs were the site of the August 21 attack that a UN report found included the use of the nerve gas sarin. They were home to more than two million people before the war, but it is unclear how many are there now.
In some hard-hit areas such as the western suburb of Moadamiyeh, people are running out of food and are mostly relying on lentils, olives and dried figs, according to residents and activists.
"We have no food, no milk and no medicine," said a woman from Moadamiyeh, who identified herself by her nickname Um Lujain for fear of government reprisals. "We are surviving on one meal a day."
Um Lujain said her 18-month-old daughter had lost half her weight and spends most of her days sleeping. The woman said her daughter's diet is based on the liquid she makes by boiling lentils.
"There has been no child formula or bread for about a year," the woman said. She added that sometimes rebels find expired boxes of powdered milk in abandoned shops or pharmacies, and people still give it to their children for lack of food.
According to the Moadamiyeh Media Centre, six people have died of starvation over the past 20 days: two women and four children aged 18 months to seven years. It added that 15 other children are in intensive care in clinics, suffering from malnutrition.
On Monday, the opposition Syrian National Coalition accused government forces of tightening their months-long siege. "Assad's forces are starving people to death in those areas," the coalition claimed. "Famine looms in the horizon."
Rana Obeid, the 18-month-old girl, was the latest to die on Monday. An amateur video showed her lying on a bed, her ribs visible and her stomach bloated.
Khaled Iriqsousi, head of the Syrian Arab Red Crescent, said that the organisation had not entered Damascus suburbs for five months because of the fighting.
Iriqsousi said by telephone that one of the most serious problems is that children are not getting vaccinated. "This will affect generations," he warned.