Teachers have warned that Prevent is "shutting down" debate in schools Peter Macdiarmid/Getty Images

Teachers have overwhelmingly called for the removal of the government's anti-radicalisation strategy, Prevent, warning that it is "smothering the legitimate expression of political opinion". The strategy is aimed at combatting extremism, but it has been slammed as fostering "suspicion and confusion" rather than safety.

Since Prevent took effect last summer, 90% of 4,000 referrals resulted in no further action being taken, according to the National Union of Teachers (NUT). The body's annual conference in Brighton also heard warnings that the anti-radicalisation policy is stopping pupils and teachers from discussing "challenging ideas" in the classroom, leaving them to look in "darker places".

"It's leading to a situation where teachers are finding it more difficult to seize opportunities to discuss important issues," said NUT executive member Alex Kenny. "When that happens, we are in danger of abandoning young people to the dark places they can find elsewhere, on the internet and elsewhere, without any hope of any mediation by us."

The motion also said that the programme was being used "against a background of increased attacks on the Muslim community and risks being used to target young Muslim people". Exorbitant referrals include the case of a four-year-old child who mispronounced the word "cucumber" as "cooker bomb". Another widely criticised example was that of a 10-year-old Muslim pupil who mistakenly wrote that he lived in a "terrorist house" as opposed to a "terraced house".

The motion said: "There is a danger that implementation of Prevent could worsen relationships between teachers and learners, close down space for open discussion in a safe and secure environment and smother the legitimate expression of political opinion." The motion asking the government to scrap Prevent and develop an alternative strategy was carried.

Speaking after the vote, NUT General Secretary Christine Blower said: "Evidence shows that grooming by extremist groups happens mainly on social media sites, not on school premises.

"Schools' best contribution to countering any behaviour that could be a problem is by encouraging discussion. Some aspects of Prevent inhibit this and it is for this reason that we need a review of the strategy to find the right, and best way to protect children and young people," she added. "The NUT is calling on the government to involve the profession in developing alternative strategies to safeguard children and identify risks posed to young people."