A United Nations humanitarian official on Friday appealed for more than $4 billion in life-saving aid for over 10 million Syrians, saying that the largely forgotten crisis in the country remains "one of the deadliest crises for civilians in the world."

Adam Abdel-Mawla, the resident coordinator in Syria for the UN Office for the Coordination of Humanitarian Affairs, made this appeal days after Syria marked the thirteenth anniversary of the conflict that has claimed nearly half a million lives and destroyed large parts of the country.

Abdel-Mawla told reporters in Geneva: "Today, we face an unprecedented situation in Syria, one we cannot ignore. Failure to act will be costly for all of us and will inevitably lead to further suffering."

He added that about 16.7 million people need some form of humanitarian assistance in Syria, an increase from 15.3 million last year. There are more than 7 million internally displaced persons, and almost a similar number of refugees in other countries, including neighboring Jordan, Lebanon, and Turkey.

The war has left 90% of Syria’s population below the poverty line, with millions facing cuts in food aid due to a funding shortage, and the UN World Food Programme ended its main aid program in the country in January.

The UN official added, "The Syrian crisis remains one of the deadliest crises for civilians in the world," noting that hostilities continue to sweep through different parts of Syria and have recently seen a sharp increase, especially in the north.

He also pointed out that the war waged by Israel against Hamas in Gaza has provided cover for further military activity in parts of Syria.

Abdel-Mawla said: "We have seen the world’s attention focus on Gaza, and that has provided a kind of distraction that allowed a significant escalation of hostilities in the northeast of the country without much attention from the international community to this situation."