Nearly 2,000 children have been referred to the UK government's deradicalisation scheme, according to the BBC.
The statistics from the National Police Chief's Council (NPCC) show 1,839 children under the age of 15 were referred to the "Channel" scheme from January 2012 to December 2015. The programme is designed to lead people away from extremism.
Out of this figure, 415 were under the age of 10.
The numbers, which were obtained by a freedom of information request, show referrals are rising each year.
The government says the programme, which is part of a wider anti-terrorism strategy, has been successful in deradicalising participants. However one parent told the BBC that the scheme stigmatises Muslims.
"A teacher's job is to teach children and not to spy on children," said Ifhat Shaheen. Her son was taken to one side in class after mentioning the word "eco-terrorists" and asked if he was affiliated with ISIS.
"Schools are meant to be a safe place where you can have open dialogue and discussion," she said.
"It's really heart-breaking to hear that young Muslim children are being criminalised in this way for the wrong reasons and an overreaction. It stigmatises Muslims."
The government says its programme has saved lives and helped prevent radicalisation.
Security Minister John Hayes said: "This is about safeguarding and it's working. This is about protection, this is about help, this is about providing all the support you need to make sure your children are safe."
At another school the head teacher said no pupils had been referred because teachers encouraged open conversation and debate about extremism rather than shying away from it.
"Just because a young person makes an off-the-cuff remark – it doesn't make them a terrorist," said Jo Dibbs, head of Elizabeth Garrett Anderson School in north London.
"All young people will say things that they don't mean and it's our job as educators to make sure they understand what they're saying and that they can explore their ideas."
If there was still concern, only then would a referral be made, she said.
The "Channel" programme is a voluntary scheme designed to stop vulnerable people being drawn to terrorist activity. It is part of a wider package of government anti-extremist measures which include an obligation on schools, prisons, the NHS and local authorities to spot and refer individuals who display signs of radicalisation.
Today's figures come after it emerged a 10-year-old boy was questioned by police after a spelling mistake meant he wrote "I live in a terrorist house" in class. He meant to write "I live in a terraced house".
