More than 80 percent of Syria's children have been harmed by the country's conflict, including growing numbers of those who were forced to work, join armed groups or marry young because of widening poverty, the U.N. children's agency said Monday, on the fifth anniversary of the crisis.

Peter Salama, the agency's regional chief, called on donor countries to make good on money pledges made at a Syria aid conference in London last month. His agency, UNICEF, seeks $1.16 billion for 2016 to help Syria's children, including close to 3 million who are not in school.

The agency has so far received only 6 percent of the amount it seeks for this year. Salama said it would make more sense for donors to provide the funds early on and enable more effective, longer-term planning.

"Let's stop the suffering now, let's ensure that they (Syria's children) have a future, and they see that they have a future," Salama told The Associated Press. "We have an opportunity still to save this generation."

Salama spoke as the U.N. envoy for Syria, Staffan de Mistura, reconvened indirect talks in Geneva between representatives of Syrian President Bashar Assad and opposition groups trying to topple his government. The talks resumed after a fragile, partial cease-fire took hold on Feb. 27.

The Syria conflict began in March 2011 as a popular uprising against Assad that quickly escalated into civil war. Since then, more than 250,000 people have been killed. Almost half the pre-war population of 23 million has been displaced, including more than 4.8 million who fled their homeland.

UNICEF said the conflict has affected more than 80 percent of Syria's children, including 7 million who now live in poverty. This has led to growing numbers of children leaving school to work, marrying young or joining armed groups, as a way of supporting their families financially, the agency said.

In refugee camps in Jordan, one-third of marriages involve girls under the age of 18 — triple what it was in 2011.

Armed groups are recruiting more children and younger children. More than half the UNICEF-verified cases of children recruited in 2015 were younger than 15, compared to 20 percent in 2014, the report said.

The agency said it was able to confirm 354 cases of recruitment in 2015, compared to 278 in 2014.

"We now face a new and disturbing era, a new and disturbing set of patterns of violations against children's rights that pushes the frontiers of brutality, even during times of war," Salama told a news conference.

The agency verified some 1,500 cases of grave attacks on children in 2015, with 400 children who were killed and 500 wo were maimed, many in or near school. Salama said that this is "the tip of the iceberg."

"In short, no place today is safe for Syria's children," he said.