Nigeria's militant Islamist group Boko Haram said to be influenced by the Koranic phrase which says: "Anyone who is not governed by what Allah has revealed is among the transgressors."
Boko Haram, founded in 2002 has created havoc in Nigeria by bombing, assassinations and kidnaping. They have been attacking towns and villages in northern Nigeria and border regions of neighbouring Cameroon, Chad and Niger.
They launched military operation in 2009 to create an Islamic state. Boko Haram has killed thousands and displaced some 1.5 million people during a six-year campaign to carve out an Islamic state in northern Nigeria.
Designated as terrorist group in 2013 by US, has now been found using children as human bombs and targeting women and girls for particularly horrific abuse, including sexual slavery, the United Nations (UN) human rights chief Zeid Raad Al Hussein said, media reported on Thursday.
"His office had received reports of Boko Haram using children as its first line of attack, as "expendable cannon fodder," Zeid told a special session of the UN Human Rights Council in Geneva, Sydney Morning Herald reported citing Reuters.
Bodies of minors have been found strewn across such battlefields," Zeid said.
"The group has also repeatedly used young children as human bombs, including a case of a 14-year-old girl carrying a baby on her back who detonated a bomb in a marketplace," Zeid said.
At least 19 people were killed when a minor girl blew herself up at a crowded market in the restive northeast Nigerian city of Maiduguri in January, media reported.
It called for those who have committed crimes on behalf of Boko Haram to be brought before competent courts of the affected states and held accountable.
A joint offensive by Nigeria and its neighbours has succeeded in driving the group from most of the positions they controlled earlier this year, reversing militants' gains that forced Nigeria to delay its February presidential election.
Zeid said that appalling atrocities committed by the group had created a critical human rights situation not only in Nigeria, but in the whole Lake Chad region.
Both children and adults have been abducted by the group on a massive scale, he said. On April 14, 276 Nigerian schoolgirls were kidnapped by Boko Haram militants from a school in Chibok, northern Nigeria.
Women and girls have been enslaved and subjected to sexual violence, forced labour and compulsory conversion, he said, citing reports from witnesses and survivors.
He said he had received information suggesting that the security forces of Nigeria and other nations combating the insurgency had also committed human rights violations, and called for a thorough and transparent investigation.
"Such violations intensify the suffering of the people - and this can only create resentment, facilitate recruitment of new insurgents, and foster vicious cycle of greater extremism," he said.
The insurgency has sharply reduced farming activity and many people are facing severe food shortages, Zeid told the council.
"Because the farms of northern Nigeria provide produce across the Sahel, this also means that the price of several basic foods has risen sharply across the region," he said.
The current dry season has intensified Boko Haram incursions into Cameroon, Chad and Niger, spreading bloodshed and desolation even more widely, the rights chief said.
"What was initially a localised crisis is fast growing to very disturbing regional dimensions," he added.
(With inputs from agencies)