At least 83 children were killed in conflict zones throughout the Middle East and North Africa last month, according to the United Nations children's agency.
The victims died as a result of fighting throughout January in Iraq, Libya, Palestine, Syria and Yemen, UNICEF said in a statement released on Monday.
A number of the children were killed during suicide attacks; others froze to death as they attempted to flee areas in which fighting was taking place.
Geert Cappelaere, UNICEF's regional director for the Middle East and North Africa, called the deaths "unacceptable" and said they represent a breach of international law.
"These children have paid the highest price for wars that they have absolutely no responsibility for. Their lives have been cut short, their families forever broken in grief," he said.
"We collectively continue failing to stop the war on children."
The Geneva Convention, which sets out the laws of conflict, calls for the protection of children during war. All 193 member states of the United Nations have ratified the convention.
At least 59 of the children were killed in Syria, according to UNICEF, which is in the grip of an ongoing civil war, now approaching its eighth year.
In Lebanon, four children were among 16 Syrian refugees who froze to death after fleeing the conflict.
Syria's civil war has claimed at least 400,000 lives and displaced 22 million people since fighting began in March 2011.
In Yemen, 16 children died during January with UNICEF receiving reports of casualties on a "daily basis", according to Cappelaere.
A suicide attack killed three children in the Libyan city of Benghazi, where three others were killed while playing near an unexploded bomb that detonated.
Other victims included a boy shot dead near Ramallah, in Palestine, and a child killed by a bomb in the Iraqi city of Mosul.
Conflicts across the Middle East and North Africa have taken a "devastating toll" on children in the region, Cappelaere said.
"Not hundreds, not thousands but millions more children in the Middle East and North Africa region have their childhood stolen, maimed for life, traumatised, arrested and detained, exploited, prevented from going to school and from getting the most essential health services; denied even the basic right to play," he said.