Naxals have recruited nearly 4,000 children, including girls, as part of a recruitment drive to strengthen depleted cadre base.
Official sources said the children were recruited for gathering intelligence about movement of security forces, collect rations and work as couriers.
The recruitment drive has been going on in all Naxal-affected states but Chhattisgarh, Odisha and Jharkhand have witnessed the most, they said.
While the age of boys is as low as 10 years, the average age of girls is 14-15 years, the sources said.
The girls were also being used for cooking and other manual works for the cadres, particularly the senior ones, they said.
The home ministry has asked the affected states to take necessary steps to stop such activities of the Maoists and try to rescue the children from their clutches.
There were 285 incidents of Naxal violence from May to July this year in which 117 people lost their lives including 47 in Chhattisgarh, 37 in Jharkhand and 15 in Bihar.