More than 1,800 children have been referred to a de-radicalisation programme over the last four years, records released under freedom of information laws have revealed.
Some 415 children aged 10 and under and 1,424 aged 11 to 15 in England and Wales were referred to the Channel scheme, figures obtained by the National Police Chiefs' Council (NPCC) show.
The 1,839 children were earmarked for the programme, set up after the London bombings to stop youngsters falling into extremism, between 2012 and 2015 as fears were raised that they were at risk of radicalisation.
Full details of who made the referrals have not been kept but, of those that were recorded, 771 were highlighted by schools. Local authorities, police, faith institutions and health services also made recommendations, according to the documents.
The West Midlands had the highest number of referrals, with 126 youngsters up to the age of 10 and 283 older children. Wales had the lowest with 20 cases.
Sally Bates, of the National Association of Head Teachers (NAHT), said some young children had watched beheading videos with relatives.
She told the BBC: "That does raise a number of concerns and that's where I can understand that referrals are then made from teachers."
Since last July, teachers have been legally obliged to report any suspected extremist behaviour to police as part of the Government's Prevent anti-radicalisation strategy.
It emerged on Wednesday that a 10-year-old Muslim boy was quizzed by police after mistakenly writing that he lived in a "terrorist house" rather than a "terraced house".
The youngster made the error during an English lesson at a Lancashire school, and the following day police arrived at his home to interview him and examine the family laptop.
A London mother has told of a similar incident after her 14-year-old son was questioned by counter-terrorism officials when he mentioned the word "eco-terrorists" in school.
Ifhat Shaheen told the BBC her son was taken aside at Central Foundation School and asked if he was affiliated to the Islamic State group.
"A teacher's job is to teach children and not to spy on children," she added.