Doctors Without Borders (MSF) said on Saturday that at least 16 more people have died of starvation in the besieged Syrian town of Madaya.
The United Nations reached an agreement with the Syrian regime to deliver aid into besieged Madaya in early January as a result of a months long siege by the regime of Bashar al Assad.
MSF reported people that the number of people who have died from starvation has risen to 46 since December.
But the medical charity said the real toll could be even higher.
"MSF has clear medical reporting for 46 starvation deaths since December 1," the group said in a statement.
Syria’s opposition wants to immediately implement UN Security Council resolutions including an end to sieges before committing to new negotiations.
Madaya is one of the four towns included in a rare deal last year that was intended to halt fighting and allow the entry of humanitarian aid.
However, despite the deal the UN and other aid convoys have limited access to Madaya and Zabadani which is under rebel control but besieged by the regime. On the other side Fuaa and Kafraya are under regime control but besieged by the rebels.
Conditions in Madaya have reportedly been among the worst, with about 42,000 civilians there surrounded by government troops who have laid mines around the town to prevent people leaving.
"The real number is almost certainly higher, as MSF is aware of reports of people dying of starvation in their homes,” MSF said.
Citing medics it supports in the town, MSF said there were at least 320 cases of malnutrition in the town, including 33 that were so severe that the individuals could die without prompt treatment.
"It is totally unacceptable that people continue to die from starvation, and that critical medical cases remain in the town when they should have been evacuated weeks ago," said MSF's director of operations Brice de le Vingne.
"The warring parties responsible for these besiegement strategies need to allow unhindered medical and humanitarian access immediately," he added.
The UN estimates that around 486,700 Syrian people are living under towns besieged by the Assad regime, rebels or the DAESH terrorist group.
The UN's aid chief said this week that 75 percent of its requests for aid deliveries in Syria went unanswered by the government.