At least 15 Palestinians have died from starvation since last September in the besieged Yarmouk refugee camp, just south of Damascus, the UN Relief and Works Agency (UNWRA) told Agence France Presse on Monday.
UNRWA spokesperson Chris Gunness said: "We have received reports over the weekend that at least five [more] Palestinian refugees in the besieged refugee camp of Yarmouk in Damascus have died due to malnutrition, bringing the total number of reported cases [of starvation] up to 15."
He warned of the deteriorating situation in the camp, where 20,000 Palestinians have been trapped with limited food and medical supplies, noting that: "Since September 2013, we have not been able to enter the camp in order to provide the necessary assistance required by the people."
He added, "The continued presence of armed groups that entered the area at the end of 2012 and its closure by government forces have thwarted all our humanitarian efforts."
Armed opposition forces are in control of the majority of the camp, which is the largest Palestinian refugee camp in Syria. Regime forces have besieged the camp for almost a year now, resulting in a humanitarian crisis, and the displacement of tens of thousands of its 170,000 residents.
The Syrian Observatory for Human Rights reported on Friday that five more people had died of hunger in the camp, including an elderly man, a woman and a person with special needs.
UNRWA launched a humanitarian appeal on 20 December to allow the agency to provide more assistance to the residents of Yarmouk, stressing that the conditions of life in the camp are extremely tragic, and that about 20,000 people are still trapped inside.
"If this situation is not addressed urgently, it may be too late to save the lives of thousands of people, including children," Gunness warned.
He said that UNRWA is calling on "all parties to immediately heed their legal obligations and facilitate the urgent provision of humanitarian assistance to Yarmouk and other Palestinian refugee camps".
Syria is home to almost 500,000 Palestinian refugees, around half of whom have been displaced by the deadly conflict that broke out in March 2011, becoming refugees for a second time.
The Syrian conflict has so far led to the deaths of more than 126,000 people, with nearly three million refugees fleeing to the neighbouring states.