Video footage has shown an enforcement officer who allegedly threatened children with a £80 fine complaining they were protesting 'too loudly'.
Pupils as young as Year 8 were allegedly told by an enforcement officer from Kingdom Services Group last Friday that their protest about climate change was "anti-social behaviour" and that they could be given tickets if they did not stop.
A Kingdom spokesman told the Peterborough Telegraph "there couldn’t have been an intention" to issue the fine as the officer's body-worn camera had not been switched on.
But footage sent into the PT shows a Kingdom officer describing the protest as "anti-social behaviour" as it was "too loud".
The video sees the officer tell Fiona Radic, who is defending the protesters: "Under the Anti-social Behaviour, Crime and Policing Act 2014 they need to stop shouting as loud as they are because it is classed as anti-social behaviour."
A lawyer then gets involved. He says: "That's hilarious. Who tells anyone how loud, loud is?"
The enforcement officer replies: "If it's disturbing the public."
The officer is then asked if there have been any complaints, to which he replied "no," before adding: "I'm an enforcement and prevention officer. I'm preventing."
The youngsters told the PT the threat of the fine was removed once they made it clear their protest had been sanctioned.
Kingdom is contracted by Peterborough City Council to patrol areas covered by Public Space Protection Orders, including one in the city centre.
This authorises them to issue fines for littering, spitting, defecating and begging, as well as cycling on Bridge Street. Its staff are allowed to hand out fines of £80, with the firm keeping £45 of the proceeds.
Several councils have broken or not renewed their contracts with Kingdom, but the firm had its contract extended with Peterborough City Council a few months ago after an initial 18 month period.
A spokesperson for the city council said: "We believe that on this occasion a misunderstanding between a group of young people and Kingdom enforcement officers occurred during a protest event.
"The protest was quite loud and mistakenly perceived to be anti-social behaviour in breach of the Public Space Protection Order. Officers initially asked the group to stop before they realised what was happening.
"We have since spoke to Kingdom about their handling of this incident and have reminded enforcement officers of their powers and responsibilities."
Young people were protesting about climate change across the country on Friday, including in Cathedral Square where school and university students from Peterborough were calling for immediate environmental action both nationally and locally.
One of the protesters, Olga, described being spoken to by the Kingdom officer.
"He said we were presenting anti-social behaviour and that we should do it silently as people may be offended," she claimed.
"We said we're not being racist, homophobic or discriminatory and that it is an approved protest, to which he kindly backed away."
Other members of the group made similar claims.
Green Party city councillor Julie Howell also witnessed the incident. She said: "It was non-violent. They were standing with megaphones and doing a march around Cathedral Square.
"He said what they are doing might be offensive. I said 'they are protecting the planet, it's offensive to stop them'.
"He was threatening to fine them if they did not stop. They are children.
"It was heavy handed and he misinterpreted the situation."
A Kingdom spokesman said: "There couldn’t have been an intention to issue (a fine) as the camera wasn’t switched on as per standard operating procedure."
Despite the threat of being fined, the protesters, who were holding banners and chanting, said the overall reaction from the public had been largely positive.
Hannah Hughes said: "Hopefully some people will come next month. We are going to do this every month until action is taken.
"Locally we are trying to get Peterborough City Council to declare a climate emergency. Peterborough is supposed to be the environment capital of the UK but has not declared a climate emergency. Many cities have done that."
Climate emergencies have previously been declared in Manchester, London and Edinburgh, as well as by many other councils, with authorities agreeing measures to try and become carbon neutral.
Peterborough City Council's cabinet member for waste and street scene Cllr Marco Cereste said he agreed with the protesters' concerns, adding: "We as an authority take the environment very seriously and are looking at all areas to see what we can do and what we can afford to do."
Cllr Cereste, who stated that he would be happy to meet the protesters, also outlined efforts the council is making on the environment.
He added: "From now on anybody that's got more recycling than can go into a green bin, if they put that recycling in a clear, plastic bag the bin collectors will take it. That will make a bit of a difference.
"We want to improve recycling rates quite dramatically and are looking at the best way to do that. The new recycling centre is a huge improvement on what we had before and that will make a difference. We're now putting together a business plan to look at changing the vehicles staff take to the depots and machinery to electric."
Among those to take part in Fridays protest, which was in the school holidays, were pupils from The King's School, Thomas Deacon Academy and Stamford Endowed Schools, as well as university students.
A similar protest had been held on March 15 involving more than one million young people across the world, with many missing school to take part.