One of the most prominent investigators into antisemitism had his YouTube account mistakenly deleted because it contained examples of the hate speech the platform is now cracking down on.

The video site began a clamp down this week on Holocaust denial, after social media sites were accused of failing to stem its spread on their platforms.

David Collier tweeted that YouTube had barred his videos on Thursday "probably because, as a fighter against antisemitism, I share examples of it".

"It's so hurtful. Hours and hours of unique, irreplaceable footage gone," he said. "Oh the antisemities are dancing today!"

But later on Thursday, he received an email saying his account was not in violation and had been restored.

Mr Collier has been behind several investigations into Labour antisemitism. He revealed Jeremy Corbyn had been a member of the infamous Facebook group Palestine Live, which was rife with Holocaust denial.

He has published reports detailing the antisemitic social media posts by Labour activists and members.

Speaking before the account was restored, Mr Collier said: "“At first I received an email saying my account had been suspended because of hate speech. I launched an appeal but it was hard to know what to say because I had no idea why they had suspended me in the first place.

"I assumed it was because in my videos I expose antisemitism. I have live and recorded footage of antisemitism on my account because I am documenting it and exposing it to people to see.

"It was frustrating to think I’d have lost all the content. It was like deleting history books it makes no sense.”

Before Mr Collier's account was restored, Mark Gardner, from antisemitism watchdog the Community Security Trust, said: “This is an appalling decision by YouTube, shutting down a leading anti-racist campaigner, whilst of course still hosting countless examples of real racism, Jew-hatred and incitement.”

YouTube confirmed it had suspended the account in error.