Shares in Twitter have fallen by more than 12pc after a short seller accused the company of being "The Harvey Weinstein of social media" for failing to deal with harassment.

The note by Citron Research called the company toxic to investors and advertisers after a damning report by the human rights organisation Amnesty International which laid bare the scale of abuse on the social network.

“The culture of hate and anonymity should have Twitter trade at a discount to its closest peer, not a 100pc premium”, it said.

“The hate on Twitter is real and the company is not taking proper steps to curb the problem. Citron believes this story has just begun and advertisers will be forced to make more morality-based brand building decisions.”

Soon after the report was published Twitter’s share price tumbled. The company's failure to crack down on hateful and abusive messages has been an ongoing problem despite repeated efforts to tackle trolls.

On Tuesday, Amnesty released a report with Element AI, a software company, which found that 7pc, or 1.1 million tweets, sent to women in the UK and US last year were “problematic” or “abusive”. Women of colour were 34pc more likely to be mentioned in offensive tweets than white women.