United Nations: Secretary-General Ban Ki-moon has expressed shock at the escalating recruitment and killing of children in conflicts last year especially in Afghanistan, Syria, Yemen, Iraq, Somalia and South Sudan.

The UN chief's annual report on children and armed conflict released yesterday said the scale and increasing severity of grave violations included continuing large-scale abduction of children and aerial attacks by some governments and international coalitions which killed and maimed many youngsters.

Ban called on all parties to conflicts to immediately end violations against children and take measures to prevent the recruitment, killing, abduction and sexual abuse of children caught in conflicts.

He warned that combatants who violate children's rights "will find themselves under scrutiny by the United Nations" and stressed that accountability remains a key priority.

The UN Security Council took the first major step to prevent the victimization of young people in war zones in 2005 by approving a resolution to identify governments and armed groups that recruit child soldiers. In 2009, the council voted to name and shame countries and insurgent groups engaged in conflicts that lead to children being killed, maimed and raped.

Last June, the council voted unanimously to name and shame governments and armed groups that abduct children. Yesterday's report names nine government security forces and 51 armed groups that committed grave violations against children last year.

New additions to the list include the Saudi Arabia-led coalition and Shiite Houthi rebels in Yemen for killing and maiming children and attacking schools and hospitals, and South Sudan's government forces known as the SPLA for carrying out more than 100 incidents of sexual violence against children.

The Civilian Joint Task Force in Nigeria, who are local residents fighting Boko Haram extremists, was listed for recruiting and using children, with more than 50 verified cases in 2015, and Raia Mutomboki 5, a large rebel group in eastern Congo, was listed for recruiting, using and engaging in sexual violence against children.

In response to last year's council resolution, the report for the first time lists six armed groups for abducting children al-Shabab militants in Somalia, Nigeria's Boko Haram, the Lord's Resistance Army in Central African Republic and Congo, the Taliban in Afghanistan, and South Sudan's SPLA.

The report said children were disproportionately affected by the intensifying conflict in Afghanistan, which recorded the highest number of child casualties in 2015 since the UN began documenting civilian deaths and injuries in 2009.

The UN said it verified 1,306 incidents resulting in 2,829 child casualties 733 killed and 2,096 injured. The casualties included 42 per cent attributed to armed groups including the Taliban, 23 per cent to Afghan forces and pro-government militias, and 55 to international forces, mainly from airstrikes, the report said.