The annual report on children and armed conflict for 2018 released on Tuesday also said that children continued to be killed or injured in operations by the security forces in Kashmir and in areas of Maoist activity. It noted that there were reports of sexual violence against girls by security forces in Kashmir citing the Kathua rape case.
Guterres, however, also welcomed "the government's measures to provide protection to children, notably through the National Commission for Protection of Child Rights."
"I encourage the government to put in place prevention and accountability measures to hold perpetrators of grave violations to account in view of ending and preventing grave violations against children," he added.
In Kashmir, the report said, "Five children, some as young as 14, were reportedly recruited by militant groups, including by Hizbul Mujahideen (two) and Ansar Ghazwat-ul-Hind (one). The two other children joined Lashkar-e-Tayyiba and were reportedly killed in an encounter with the government forces on December 9."
There were reports of "systematic recruitment" of children by Maoists, the report said.
It said that there were child casualties from security forces actions against Maoists in the states of Bihar, Chhattisgarh, Jharkhand, Maharashtra and Odisha.
Giving examples, the report said that on April 22 last year eight children were reportedly killed during an anti-Maoist operation by district-level special forces in the district of Garhchiroli, of Maharashtra, in which at least 40 Maoists were killed.
In Kashmir "31 children between the ages of 7 and 17 were allegedly killed, including during government armed forces operations" and "at least 150 children, some as young as one, were reportedly injured, mostly by pellet bullets used by the security forces," it said.
It said that "allegations of the perpetration of sexual violence against girls by the security forces in Kashmir were reported".
"For instance", the report said, "an 8-year-old girl was reportedly abducted, drugged, raped for three days and murdered in Kathua district by special police officers".
Four police personnel were among six people convicted last month by a special court that tired the Kathua case.
Guterres's report said that globally "more than 24,000 grave violations against children were verified by the UN in 20 country situations".
"While the number of violations attributed to non-State actors remained steady, there was an alarming increase in the number of violations attributed to state actors and to international forces compared with 2017," it added.
According to the report, Afghanistan was the worst place children. Last year, there were 3,062 child casualties there and children accounted for 28 per cent of all civilian casualties, it said.
(Arul Louis can be reached at arul.l@.in and followed on Twitter @arulouis)
( With inputs from IANS )