The use of starvation in besieged areas of Syria is "utterly unconscionable" and constitutes a war crime, UN Secretary General Ban Ki-moon said Thursday.
In one of his strongest statements yet on the nearly five-year-old conflict, Ban said UN teams had witnessed "scenes that haunt the soul" after delivering aid to three besieged towns this week.
"The elderly and children, men and women, who were little more than skin and bones: gaunt, severely malnourished, so weak they could barely walk, and utterly desperate for the slightest morsel."
The humanitarian convoys have made two aid deliveries this week, including to the rebel-held Madaya, where dangerous levels of malnutrition was reported. Madaya had been without humanitarian assistance for three months.
While aid convoys first entered the town on Monday, it wasn't until Thursday that Ban called the use of starvation a war crime. On Wednesday, Ban's spokesman said that starvation "could very well be considered a war crime" without going any further.
"Let me be clear - the use of starvation as a weapon of war is a war crime," Ban said Thursday.
"All sides – including the Syrian government, which has the primary responsibility to protect Syrians - are committing this and other atrocious acts prohibited under international humanitarian law."
He said it was up to the UN Security Council to take further action, including referring the situation to the International Criminal Court, a move that Russia and China had vetoed in 2014.
Ban also urged all international parties to press warring parties in Syria to lift sieges, which currently affect 400,000 people, including 200,000 in areas controlled by the Islamic State; 180,000 in regions under government control and 12,000 in areas held by rebel groups.
This would be an important step toward building confidence for a political transition, he said.