The parents of the 14-year-old are taking legal action after the boy said he was left “scared and nervous” by his experience with school officials in north London, and was left reluctant to join in class discussions for fear of being suspected of extremism.

The incident gives an insight into how schools and teachers are dealing with the pressures of the government’s new anti-extremism initiatives amid mounting concern about British youngsters being lured by Isis propaganda.

According to court documents, the boy was in a French class at the Central Foundation school in May 2015 and took part in a discussion, conducted mostly in French, about the environment. The teacher and pupils were said to have discussed those who use violence to protect the planet.

The teenager mentioned that some people use the term “ecoterrorist” to describe those who take action such as spiking trees with nails to prevent chainsaws from chopping them down.

A few days later he was pulled out of class and taken to an “inclusion centre” elsewhere in the school. During this meeting the schoolboy said one adult sat behind him, and another in front of him, whom he had not seen before. That person was a child protection officer, the Guardian has learned, who had been called in to establish if concerns about terrorism were legitimate.

The boy who wishes not to be named, told the Guardian: “I didn’t know what was going on. They said there had been safety concerns raised. If you are taken out of French class and asked about Isis, it is quite scary. My heart skipped a beat.”

He said he was baffled how mentioning the phrases “L’ecoterrorisme”, which he had learned from an earlier session of the school debating society, led to him being asked whether he supported Isis.

The boy and his parents say he was asked if he was “affiliated” with Isis. The school said he was asked if he had heard of the terrorist group, according to legal papers filed by his mother. The boy’s mother said her son came home from school “visibly distressed”.

The school said it was protecting the “welfare of the child in line with statutory and non-statutory guidance including the ’prevent duty’”, the government initiative that aims to stop people turning to extremism and terrorist violence, according to the legal documents.

His parents are seeking a judicial review, arguing the child was discriminated against and was singled him out because of his Muslim heritage. They also described the prevent policy as unfair. Recently, new laws placed a “positive duty” on schools to implement it.

The school and Islington council, which controls it, declined to answer questions about the incident. However, a spokesperson for Central Foundation Boys’ school 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.”

The teenager said school friends have been supportive, especially white ones, viewing it as an injustice suffered because he is Muslim.

In the end no action was taken and the teenager has been attending the school, which is highly rated. He has been student of the week three times in last two years and said teachers were usually nice and took time to get to know the students. He has since dropped French, and ultimately wants to be a software engineer.

Last week David Anderson, the government-appointed independent reviewer of terrorism, said ”prevent” caused widespread anger among Muslim communities. “While good work is undoubtedly done under prevent, it is also the focus of considerably more resentment among Muslims than either the criminally-focused prohibitions,” he said.

In a sworn statement as part of the legal action, the teenager said he was in a morning French class when the discussion occurred. He said: “I had recently learned about eco-warriors and the demonstrations that they organise in the context of an extracurricular debating club in which I take part called Debate Mate.

“When I said this, I thought that [the teacher] looked concerned. I therefore explained what eco-warriors are, and that sometimes people who call themselves eco-warriors take action such as spiking trees with nails to prevent chainsaws from chopping them down, as the metal nails blunt the blades of the saw. I then said that some people refer to this as ‘eco­ terrorism’.”

Around one week later the teenager was in another French class when he was taken out to an “inclusion centre”. Describing what happened there, he said in his statement: “The lady behind the desk told me that she was a child protection officer. She then said to me that there had been “a safety concern raised”. I did not understand why she was talking about a safety concern and what this had to do with me. She went on to say: ‘Your French teacher … I think, mentioned you used the word terrorism.’

“I remembered the lesson and explained that I had mentioned the phrase eco-terrorism in relation to eco-warriors and protecting the environment. I explained again what they were, and that they put nails in trees to blunt the blade of a chainsaw which is why people sometimes call them terrorists. The member of staff behind the desk looked at the member of staff behind me and said: ‘Told you, he is a tree-hugger.’

“She made a hugging gesture with her arms and, looking at me, asked me if I ‘went around hugging trees’ like one of her relatives. She then asked me: ’Do you have any affiliation with Isis?’

“When she said the word Isis I immediately felt alarmed and extremely scared. I knew what Isis was as I have seen reports about them in the media. I knew that they behead and kill people. I could not think why she was asking me this or how it followed on from my French lesson … and replied no.

“The member of staff sitting behind me, who had brought me to the inclusion centre, then asked me: ‘Do the chainsaws explode?’. Before I could answer the member of staff sitting behind the desk asked: ’Do you understand why there could be a misunderstanding?’”

The boy’s mother said: “He was presumed guilty because he was Muslim. As parents we are doing the right thing but still our son is accused. There was nothing in what he said that warranted him being taken out of class and treated as a criminal.”

She said she thought prevent was causing damage and stifling discussions that could stop extremism. “If the three girls from Bethnal Green who went to Syria, if they had said in class: ‘My dream is to marry a jihadi’, their peer group would probably have slapped them down,” she said

In a response to the legal action, Central Foundation school said it should be dismissed. According to legal documents related to the case it added: “It is unarguable that at the relevant time (May 2015) the school was required as part of its safeguarding responsibilities to be aware of the dangers of radicalisation.

“The approach of alerting the designated child protection officer by email regarding inappropriate references to terrorism and for [her] to have short 10-minute conversation with the claimant was a reasonable and proportionate response.”

The school added: “This safeguarding step can not be criticised, as the school had due regard to its overarching duty to safeguard pupils and the need to prevent them being drawn into terrorism.”