A Nigerian militia group battling the Boko Haram militants in the northeast region of the country has set free 461 child soldiers from its ranks, the United Nations Children's Fund (UNICEF) said.

The militia group, Civilian Joint Task Force (CJTF), freed the children aged between 12 and 13 on Tuesday and formally handed them over to the government in the northeastern city of Maiduguri, capital of the restive Borno State.

UNICEF said that the children had been recruited to fight Boko Haram between 2013 and 2017. The CJTF was established in 2012, mainly from vigilante groups in response to Boko Haram's terror campaign. The CJTF has been credited for providing protection to local communities, forcing the terror group to flee to Sambisa forest and the shores of the Lake Chad.

Geoffrey Ijumba, the Unicef chief of Borno field office, said 3,737 children associated with CJTF have been identified to be associated with the armed conflict within the city of Maiduguri and 20 other local government areas in the state.

Out of the figure, about 1,727 have been released and have accessed reintegration services aimed at giving them skills to cope with life and become meaningful individuals, Ijumba said.

He said with the latest release, it brings the total number of children released in 2019 to 1,355. In May, 894 children were released as part of the action plan signed in September 2017 to end the recruitment and use of children as soldiers. "As children learn and acquire skills, economies have a chance to progress," the UNICEF official said, calling upon all parties in the conflict to stop recruiting and using children.