The campaigner was forced to defend himself after controversial claims he is a transphobe and a racist.

Veteran gay rights activist Peter Tatchell has accused a university student of smearing him with false allegations of racism and transphobia in what he has labelled a “witch hunt”.

Mr Tatchell was due to take part in a debate with Fran Cowling – a National Union of Students representative on LGBT issues.

However, she pulled out after claiming that he was a bigot.

Miss Cowling – a PhD student at Nottingham University – said she would only take part if Mr Tatchell withdrew from the event, as she accused him of having used racist language and signing an open letter which condoned violence against the trans community.

Despite her accusations, Mr Tatchell – who recently announced plans to reach out the Muslim community on LGBT rights – said Miss Cowling had failed to provide any evidence to support her claims.

He added that he had tried to raise the matter directly with her – before being blocked from sending emails to Miss Cowling.

“Fran Cowling – apparently acting in the name of the National Union of Students – has denounced me as a racist and a transphobe,” he told the i newspaper.

“She has a right to refuse to speak alongside me, but not to make witchhunting, McCarthy-style, untrue allegations.”

“I have never used racist language or harassed anyone. I have challenged Fran Cowling and NUS LGBT to produce evidence for these claims,” he later told the Daily Mail.

“They have failed to produce the evidence – because the accusations are untrue.

“I have supported every anti-racist and pro-trans campaign for the last 49 years,” he added.

“I’m prepared to share a platform with people I profoundly disagree with – in order to challenge and expose them.

“Free speech is one of the most precious of all human rights.”

Fans of the campaigner were quick to lend their support – including trans children’s author Juno Dawson.

“He’s worked phenomenally hard for the LGBT community and he’s sacrificed pretty much his adult life to supporting the rights of LGBT people around the world,” she said.

Mr Tatchell – who last month leant his support to a bakery that refused to bake a ‘gay’ cake – is due to lead a discussion called “Re-Radicalising Queers: should we toe the line or cause a stir?”, at Canterbury Christ Church University this evening.