The Government's adviser on social cohesion has revealed she has spoken to the teacher in Batley who was forced into hiding as a result of abuse and threats, calling for ministers to do more to tackle "freedom restricting harassment".
Dame Sara Khan, who authored a report into extremism, warned that rising hate crime could "erode our freedoms".
The Khan Review warned that towns and cities across Britain are "struggling" to deal with extremism being whipped up by Islamists and the far Right.
It concluded that in some areas there is "no infrastructure in place" to tackle conspiracy theories, disinformation and harassment.
Dame Sara Khan, who authored a report into extremism, warned that rising hate crime could "erode our freedoms"
PA
Khan told GB News that there have been "lots of teachers who have experienced threats and abuse" but said the Government is unaware of the "full scale" of the problem as the Department for Education doesn't collect data.
This came after campaigners and parents forced a teacher at Batley Grammar School into hiding for showing a cartoon of the Prophet Mohammed in class.
Speaking three years after it happened, Khan said teaching unions told her similar incidents are becoming a "growing problem", adding: "I think this is something we have to tackle. And, you know, let's be clear, this was somebody who was teaching a lesson that was part of the national curriculum that was signed off by the local authority, and he was hounded out of his job and forced into hiding in our country in the 21st century.
"That is totally and utterly unacceptable in a free and democratic society like ours."
Khan, who said she has met with the teacher multiple times, described the impact of what happened to him as "devastating".
She added: "It's not just impacted him. It's impacted his family, his children. As I write in the report, he suffers from post-traumatic stress disorder because of what happened to him at the time of the incident, which is exactly three years ago today.
"He felt suicidal because not only because of the incident and the threats to him, but because of the failure of local agencies and authorities to help him, which compounded his sense of suicidal thoughts".
A recent poll, conducted for Policy Exchange, found that teachers across the UK are self-censoring their lessons over fears of causing religious offence.
A survey of over 1,000 teachers found that 16 per cent of them have admitted to self-censoring. The think tank claims this has created a “de facto blasphemy code in schools across the country”.
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Earlier this month, ministers unveiled a new definition of extremism, which will be used to ban certain groups from accessing Government funding and meeting with officials.
The definition will apply to groups that promote an ideology based on "violence, hatred or intolerance."
The new definition, which came into force two weeks ago, will not criminalise the groups but it will deny them access to taxpayer funding and bar them from meeting ministers and officials or gaining a platform that could "legitimise" them via association with the Government.