The deaths and injuries were among more than 24,000 "grave violations" against children verified by the United Nations including the recruitment and use of youngsters by combatants, sexual violence, abductions, and attacks on schools and hospitals, it said.

According to Secretary-General Antonio Gutteres' annual report to the Security Council on Children and Armed Conflict obtained Monday by The Associated Press, violations by armed groups remained steady but there was "an alarming increase" in the number of violations by government and international forces compared to 2017.

The secretary-general's eagerly awaited blacklist of countries that committed grave violations against children during conflicts remained virtually unchanged from last year, angering several human rights groups.

Human Rights Watch and the Watchlist on Children and Armed Conflict, an international advocacy group, pointed to the Saudi-led coalition remaining on the list of parties that have put in place measures to protect children, citing a rise in child casualties by government and coalition forces in Yemen.

"The Saudi-led coalition since 2015 has committed appalling violations against children in Yemen without any evidence that it's trying to improve its record," said Louis Charbonneau, U.N. director at Human Rights Watch. "By including them once again in the 'not so bad' category of serious reformers, the secretary-general makes a mockery of the whole exercise."

Watchlist program director Adrianne Lapar said that praising "empty promises" by the coalition, also led by the United Arab Emirates, "undermines the deadly repercussions of war on children and ignores the facts on the ground."

She also asked why conflicts in Cameroon and Ukraine are "conspicuously missing from the report."

Guterres said he was "deeply concerned by the scale and severity of the grave violations committed against children in 2018, notably the record high number of casualties as a result of killing and maiming and the increase in the number of violations attributed to international forces."

According to the report, verified cases of deaths and injuries were the highest since the Security Council authorized monitoring and reporting in 2005.

Afghanistan topped the list with 3,062 child casualties in 2018, "and children accounted for 28 percent of all civilian casualties," the report said, while in Syria, air strikes, barrel bombs and cluster munitions killed and injured 1,854 youngsters "and in Yemen, 1,689 children bore the brunt of ground fighting and other offensives."

In the Israeli-Palestinian conflict, the U.N. said that in 2018 it verified the highest number of Palestinian children killed — 59 — and injured — 2,756 — since 2014. During the same period, six Israeli children were injured.

Guterres said he is "extremely concerned by the significant rise" in injuries, including by inhaling tear gas. He asked U.N. envoy Nikolay Mladenov to examine cases caused by Israeli forces "and urge Israel to immediately put in place preventive and protective measures to end the excessive use of force."

Jo Becker, children's rights advocacy director at Human Rights Watch, expressed concern that Israeli forces, U.S.-led international forces in Afghanistan, and the Afghan National Army were left off Guterres' "list of shame," and that the Somali National Army got "credit" for protecting children even though its violations increased.

According to the report, parties to the conflict in Somalia recruited and used 2,300 children, some as young as 8-years-old, with al-Shabab extremists significantly increasing their recruitment to 1,865 youngsters. Nigeria was in second place, with 1,947 children recruited, including some used as suicide bombers.

Somalia also had the highest verified figure for sexual violence against children, with 331 cases in 2018, followed by Congo with 277 cases though the secretary-general said cases remain significantly underreported, particularly against boys because of stigma. And Somalia had the highest number of child abductions last year — 1,609.

Guterres said thousands of children were also affected by 1,023 verified attacks on schools and hospitals last year.

In Syria, 2018 saw 225 attacks on schools and medical facilities, the highest number since the conflict began in 2011, he said, and Afghanistan also saw an increase with 254 schools and hospitals targeted.

"Increased numbers of attacks were also verified in the Central African Republic, Colombia, Libya, Mali, Nigeria, Somalia, the Sudan and Yemen," Guterres said.

The secretary-general also expressed increasing concern at the increasing detention of children, reiterating that "this measure should only be used as a last resort, for the shortest period of time, and that alternatives to detention should be prioritized whenever possible."

In December 2018, Guterres said, 1,248 children, mainly under the age of 5, of 46 nationalities from areas formerly controlled by Islamic State extremists, were "deprived of their liberty" in camps in northeast Syria.

In Iraq, 902 children remained in detention on national security charges, including for associating with IS, he said.

And as of December, Guterres said, Israel was holding 203 Palestinian children over security offenses, including 114 awaiting trial or being tried, and 87 serving a sentence. He said the U.N. received affidavits from 127 Palestinian boys "who during interviews with the United Nations reported ill-treatment and breaches of due process during their arrest, transfer and detention."