United Nations human rights boss Zeid Ra'ad Al Hussein said on Monday that starving Syrian civilians is a potential war crime and crime against humanity.
The top UN official also added that it should be prosecuted and not covered by any amnesty linked to ending the conflict.
"In the case of Syria, we are there to remind everyone that where there are allegations that reach the threshold of war crimes or crimes against humanity that amnesties are not permissible," al Hussein said in a news briefing in Geneva.
He also cited that people in Madaya and another 15 besieged towns and cities in Syria are dying from starvation, he said this was "not just a war crime but a crime against humanity if proven in court."
"We estimate that tens of thousands are held in arbitrary detention and clearly they need to be released," Zeid added.
Madaya is one of the towns that suffers most from starvation, with people dying in the town due to this reason everyday.
More than 20,000 children in the town of Madaya are at risk of further hunger and starvation, the United Nations Children's Fund said on Friday.
Almost 42,000 people in Madaya are at risk of further hunger and starvation and half of them are children, UNICEF spokesperson Christophe Boulierac told journalists in a press conference at the UN Office in Geneva.
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.
The Russian Federation which backs the Assad regime reportedly have killed nearly 1,400 civilians in Syria while conducting air strikes.
A statistic released by the Syrian Civil Defence Authority stated last month that civilian casualties had reached more than 1,800.