Syrian children play with a ball in a refugee camp for displaced people run by the Turkish Red Crescent in Sarmada district, north of Idlib city, Syria, Friday, Nov. 26, 2021. AP
"Syria's children have suffered for far too long and should not suffer any longer," the UN children's agency said in a statement.
A total of 9.3 million Syrian children are in need of aid both inside the country and in the wider region where they have fled, UNICEF spokesperson Juliette Touma told AFP.
"More than 6.5 million children in Syria are in need of assistance, the highest number recorded since the beginning of the crisis, more than 11 years ago," the agency statement added.
In neighbouring countries, 2.8 million Syrian refugee children depend on assistance, Touma said.
Syria's war is estimated to have killed nearly half a million people and displaced millions since it began with a brutal crackdown of anti-government protests in 2011.
It escalated into a devastating and complex conflict that drew in numerous actors including jihadist groups and regional and international powers.
"Children's needs, both inside Syria and in neighbouring countries, are growing," said Adele Khodr, UNICEF's Middle East chief.
"Many families struggle to make ends meet. Prices of basic supplies including food are skyrocketing, partially as a result of the crisis in Ukraine."
Children are among the most vulnerable and the UN warned they are bearing the brunt of the impact.
UNICEF said the agency faced a severe cash shortfall to provide aid.
"Funding for humanitarian operations is meanwhile fast dwindling," Khodr said. "UNICEF has received less than half of its funding requirements for this year."
UNICEF called for $20 million to fund "cross-border operations" in northwest Syria -- the country's last major rebel enclave -- to support "the only lifeline for nearly one million children".