Restrictions on political topics in schools will harm young people by curbing discussions about the polarised arguments and issues they are exposed to on social media, according to the government’s former mental health champion.

Natasha Devon said young people from minority backgrounds stood to be the biggest losers if the new guidelines meant teachers in England were afraid to provide students with a safe environment to debate issues.

“I work with 14- to 18-year-olds and my experience is that young people are bringing ideas from social media, from activists that they admire, into the classroom,” said Devon, who was the first ever mental health champion for schools.

“Teachers are trying to help them to make sense of those ideas, and discuss them in a way that is non-partisan. But the desire to address these things in the classroom is 100% coming from young people, it’s a not a case of indoctrination by teachers.”

This week the education secretary, Nadhim Zahawi, published guidance aimed at teachers in England, as part of an effort by the government to dampen down critical debate about the history of the British empire, and controversy over the role of leaders such as Winston Churchill.

The guidance – which is a reformulation of existing statutory regulations and legal duties – stresses the need for impartiality when teaching “contentious” issues such as imperialism. It cautions teachers against adopting or advocating “extreme” political positions such as those it claims are espoused by the Black Lives Matter movement, which is singled out by name in the document as needing to be balanced.

But Devon compared the guidance to the section 28 regulations concerning classroom discussion of homosexuality in force during the late 1980s and 1990s.

“With section 28 it didn’t say you can’t talk about homosexuality, it said you were not allowed to ‘promote’ homosexuality,” she said. “But what ended up happening is that no one talked about it and I think the same thing is going to happen now, which will harm minority students by taking away their space to explore issues like race and social justice that are affecting them all the time.”

Rowena Seabrook, Amnesty International UK’s humans rights education manager, agreed, saying: “The government’s guidance for schools is unnecessary – and it will have a chilling effect in classrooms across the country.

“Suggesting that teachers should not use material from social justice movements such as Black Lives Matter is entirely partisan, and lacks balance and safe spaces for students to explore issues labelled ‘controversial’.”

Natasha Robinson, a researcher at the University of Oxford who studies how controversial subjects are taught in history classrooms, said the guidance “leaves teachers with the impression that they could be bludgeoned for most of what they teach”.

She added: “Giving teachers a list of thing that they shouldn’t talk about, or of things they should avoid, is very different from giving them practical strategies in the classroom. When a student makes a racist comment or a very partisan political comment, how do teachers deal with that? That takes a great deal of skill. And this report – because it’s so vague – just comes across as scare-mongering.”

Nick Lowles, chief executive of Hope Not Hate, a campaigning antifascism and antiracism group, said the DfE’s guidelines seemed designed to create headlines about “culture wars” rather than improving education.

“Turning the need to teach children about racism and prejudice into a political football is cynical and does little to help schools navigating this complex topic,” Lowles said.