A teachers’ union has attacked a “racist” counter-extremism scheme used in schools, after it emerged a 14-year-old Muslim boy was taken out of class for saying the term “eco-terrorism”.

In May, the Central Foundation Boys’ School pupil had been in a French class, taking part in a discussion about the environment, when he mentioned “l’ecoterrorisme”.

A few days later, the boy was taken out of class and questioned by a child protection officer.

He claims to have been asked if he was “affiliated” with Islamic State, and his parents are now said to be taking legal action.

The boy was questioned as part of the government’s Prevent scheme, which aims to protect children from radicalisation.

But Islington NUT, which represents the majority of teachers in the borough, said Prevent “demonises Muslims, inhibits free speech and encourages teachers to act as spies in the classroom”.

Ken Muller, joint secretary of the union, said: “Would this have happened to a white British student? No it would not. Prevent is aimed at Muslims. It is racist. It is Islamophobic.

“Schools should be places where children feel they can safely express their views – and sometimes have them challenged – without fear of being hauled out of their classrooms and interrogated by strangers.

“The government’s demands that anyone refusing to subscribe to their version of ‘British values’ – or holding ‘non-violent extremist views’ – should come under suspicion is a threat to all of us.

“Two million people, including thousands of teachers, marched against war with Iraq back in 2003. Last year tens of thousands protested across the UK against the Israeli war on Gaza and UK and US government support for Israel. Are we all extremists too?”

A spokesman for Central Foundation, Cowper Street, refused to comment on the 14-year-old’s case, but said: “The safeguarding and the wellbeing of our young people is our primary concern.

“The school is confident that its safeguarding policies and the work of the professionals in the operation of these policies are proportionate, justified and place the wellbeing of the child to the fore.

“We do not comment on confidential matters relating to individual young people.”