The mother of a 12-year-old boy has criticised Thames Valley police for taking her son out of lessons because he was planning to picket David Cameron's constituency office today.

Nicky Wishart, a pupil at Bartholomew School, Eynsham, Oxfordshire, organised the event on Facebook to highlight the plight of his youth centre, which is due to close in March next year due to budget cuts.

The protest, which was due to take place today, has attracted over 130 people on Facebook, most of whom are children who use youth centres in Cameron's constituency, Witney.

Wishart said that after the school was contacted by anti-terrorist officers, he was taken out of his English class on Tuesday afternoon and interviewed by a Thames Valley officer at the school in the presence of his head of year. During the interview, Wishart says that the officer told him that if any public disorder took place at the event he would be held responsible and arrested.

Speaking to the Guardian, Nicky Wishart said: "In my lesson, [a school secretary] came and said my head of year wanted to talk to me. She was in her office with a police officer who wanted to talk to me about the protest. He said, 'if a riot breaks out we will arrest people and if anything happens you will get arrested because you are the organiser'.

"He said even if I didn't turn up I would be arrested and he also said that if David Cameron was in, his armed officers will be there 'so if anything out of line happens ...' and then he stopped."

Wishart, who describes himself as a "maths geek" said he was frightened by the encounter. "I was really scared. Normally I'm a confident speaker but I lost all my confidence. My mum was worried, and I was worried and I didn't know what to do."

Wishart's mother, Virginia Phelps, 41, said: "On Monday I got a phone call in the afternoon at the school from one of the senior staff members, saying, 'we've had the police here, it's to do with the anti-terrorist group, they've taken an interest in something Nicky's posted on FB'.

"I was under the impression that the police would come to the house and speak with us in the evening but I am absolutely fuming that they spoke to him when I wasn't present, especially when I live just 10 minutes from the school."

Speaking about the youth club, Phelps, a mother of three added, "Over the last few months, the kids have been trying to keep the youth club open, raising money by cleaning cars. They've raised £140. Through the club they've been had all sorts of experiences that I couldn't afford to give them myself."

Despite the police visit, Wishart said he would continue with the picket today and he would be delivering a letter to Cameron's staff about the youth centre closure.

A spokeswoman for Thames Valley police said: "We have dedicated officers who work in partnership with all the schools in our area to make sure young people remain in education and in a safe learning environment.

"On Tuesday 7 December, our schools officer for west Oxfordshire attended the school in Eynsham and spoke to a 12-year-old boy in the company of the pupil's head of year, about a planned protest. This was not with the intention of dissuading him from organising it, but to obtain information regarding the protest to ensure his and others' safety. As with any demonstration, we always aim to facilitate a peaceful protest."

The headmaster of Bartholomew school, Andrew Hamilton, refused to give comment saying that it was something that the school was "dealing with internally".