Thousands of people may have starved to death in areas deliberately cut off by Syrian government troops and the Islamic State (IS), the United Nations human rights chief said on Monday.
Zeid Ra'ad al Hussein said some of the estimated half a million people trapped in besieged towns and villages had been cut off for years.
"The deliberate starvation of people is unequivocally forbidden as a weapon of warfare. By extension, so are sieges, which deprive civilians of essential goods such as food," he said.
Dozens of people are reported to have died of starvation in Madaya, a mountain village which brought global attention to the plight of besieged Syrians when photographs and video of its emaciated residents emerged last month.
Syrian President Bashar al-Assad has used a "siege and starve" technique on Madaya and other rebel-held areas in an attempt force them to capitulate.
Speaking as the UN and partner organizations get ready to deliver life-saving aid to about 154,000 besieged Syrians in the next five days, Zeid warned the situation could be even worse than first imagined.
"Thousands of people may have starved to death," he said. The course of the war had seen Syrian people's human rights "shockingly violated," he added, highlighting the fact that at least 10 hospitals and other medical units have been damaged or destroyed just since the beginning of the year.
"Neighborhoods, schools, and packed marketplaces have been hit by tens of thousands of air strikes, thousands of barrel bombs have been thrown out of helicopters onto streets and homes," he said. "[Some parties] some parties are targeting medical units deliberately, or with reckless disregard."
Pending approval from parties to the conflict, the UN will deliver aid to about 1.7 million people in hard-to-reach areas in the first quarter of 2016, UN Resident Coordinator in Damascus, Yacoub El Hillo, said on Sunday.
Aside from almost 500,000 people living under siege, there are estimated to be another 4.6 million Syrians who are hard to reach with aid.
The UN hopes to deliver aid to Moadamiya on Monday, the "four towns" of Zabadani, Kufreya, Foua, and Madaya on Wednesday, and Kafr Batna on Friday.
But the biggest single siege, of about 200,000 people in Deir ez-Zor, is not affected by the cessation of hostilities because the besieging IS forces are excluded from the agreement.
The UN attempted an airdrop there last week but high winds meant all 21 tons of food went off target or missing, or their parachutes failed to open and they were destroyed.
During the course of the five-year war more than half of Syria's population has been killed, injured, or displaced.
Over 250,000 people have been killed and over one million injured, 4.6 million Syrians have been forced to leave the country, and 6.6 million are internally displaced.
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