GENEVA — Around 14 million children are suffering hardship and trauma from the war in Syria and Iraq, the United Nations children’s agency said on Thursday, highlighting the needs of children struggling to cope with severe violence, and the danger to the rest of the world of failing to help a generation preyed on by extremist groups.

“Violence and suffering have not only scarred their past, they are shaping their futures,” Anthony Lake, Unicef’s director, said in a statement released on Thursday with a report on the plight of 5.6 million children in Syria and two million more who have fled as refugees. Close to three million children in Iraq and 3.6 million children in neighboring countries bearing the brunt of the influx are affected by the conflict, Unicef estimated.

“As the crisis enters its fifth year, this generation of young people is still in danger of being lost to a cycle of violence — replicating in the next generation what they suffered in their own,” Mr. Lake said.

Unicef’s report was one of a slew of statements by international relief agencies detailing the plight of civilians in Syria in a conflict that has killed more than 200,000 people.