Police are investigating a series of sexually explicit and violent tweets sent to an MP after she spoke out in support of a feminist campaigner who received threats to rape and kill her via Twitter.
Walthamstow MP Stella Creasy faced a vicious online attack from internet "trolls" after she gave her backing to Caroline Criado Perez, who received the barrage of abuse following her successful campaign to have a woman's picture placed on a new banknote.
The politician retweeted some of the sinister messages to her 30,000 followers as she warned the "morons" behind the abuse would face justice.
Scotland Yard said last night "officers in Waltham Forest received an allegation of malicious communications from an MP. The allegation relates to comments made on Twitter and is currently under consideration".
Ms Criado Perez, a freelance journalist, organised a campaign which included a petition signed by more than 35,500 people after the Bank of England decided to replace Elizabeth Fry with Winston Churchill on new £5 banknotes.
Her campaign led to the announcement that Jane Austen would feature on the new £10 note from 2017, but led to a litany of hostile and menacing tweets against her.
Ms Criado Perez described how the online abuse had left her feeling "under siege" and terrified in her own home.
She told BBC2's Newsnight: "It has consumed my life both physically and emotionally. I've not really had much sleep.
"The threats have been so explicit and so graphic that they've sort of stuck with me in my head and have really put me in fear, I realised."
But in a defiant message to her tormentors she said: "I would like to say I think they are completely pathetic. If they think they are going to drive me or any other woman off the internet they are going to be sorely disappointed."
She criticised the response from Twitter and claimed to have been blocked by Mark Luckie, one of its senior managers, after he was made aware of her ordeal.
"I can't begin to imagine why, either from a decent human being perspective or just from a PR perspective. I would imagine Twitter is pretty embarrassed about that."
Police have questioned a 21-year-old man in connection with the torrent of abuse. He has been bailed to a date in mid-September following his arrest in Manchester on suspicion of harassment offences, Scotland Yard said.
It follows a complaint made on Thursday to detectives in Camden, north London, who are continuing their inquiries, the force added.
Critics have called for Twitter to take faster and stronger action against online thugs in the wake of the abuse, and Ms Creasy has criticised the micro-blogging site's security policies.
She told BBC Radio 4's The World At One: "This is not about Twitter, this is about hatred of women and hatred of women who speak up.
"And indeed, some of those people sending the messages have been absolutely explicit about that.
She added: "Twitter needs to be explicit that sexual violence and sexual aggression will not be tolerated as part of their user terms and conditions.
"We can all challenge these people and indeed when this happens to me in other occasions I tend to retweet it so people can say 'This is not acceptable'.
"But we also need a platform for when things are not dealt with by users, when actually users do not realise that they are being misogynist, they are being aggressive or that actually they are trying to shut other people's free speech down."
She continued: "I think we are evolving how we understand the impact of the internet and social media on crime and how it's committed. But let's be very clear, this isn't about free speech.
"Free speech is incredibly important on and offline, but it's not free speech for someone to be threatened with rape. We have to have ways of dealing with that and we mustn't misunderstand the level of cyber harassment taking place in this country.
"That's what we are looking for Twitter to play a key role in. Because actually if Twitter didn't exist, these people would still propagate these kind of views."
Despite her warnings that she would report internet trolls to the police, Ms Creasy was last night still receiving tweeted threats of sexual violence, which she retweeted.
Yesterday the chairman of the Association of Chief Police Officers (Acpo) communications advisory group said Twitter had a lot more work to do in combating online threats.
Andy Trotter told BBC Radio 4's The World At One: "They need to take responsibility as do the other platforms to deal with this at source and make sure these things do not carry on.
"They need to make it easier for victims to report these matters and, from a police perspective, they need to know that they can report these things to us."
Twitter said it planned to include a button for reporting abuse within every tweet, which is already available on its iPhone app.
Del Harvey, Twitter's senior director, trust & safety, said on the website's UK blog that the firm was "not blind to the reality" that some users would use the service to post abuse.
Ms Harvey said: "While manually reviewing every tweet is not possible due to Twitter's global reach and level of activity, we use both automated and manual systems to evaluate reports of users potentially violating our Twitter rules.
"These rules explicitly bar direct, specific threats of violence against others and use of our service for unlawful purposes, for which users may be suspended when reported."
Tory MP Claire Perry, who has been advising David Cameron on measures to tackle the spread of extreme pornography and child abuse on the internet, also revealed the extent of the abuse she had received from Twitter users.
The Devizes MP wrote: "I am tempted to shut down my Twitter account given the trolling going on incl. to me - but that would be giving in."In a message to her Twitter user @epivalent said: "Please disappear into obscurity and/or alcoholism. or die, whatever. the main thing is you should f*** off and never return."
In another foul-mouthed posting a Twitter user going by the name @badassday said: "Devizes is in Wiltshire, right? That's where there isn't any porn, & it's still 1953, right? Hello @claire4devizes, u stupid dinosaur t***."
Meanwhile television classicist Mary Beard silenced an internet troll after naming and shaming him on Twitter.
Ms Beard, professor of classics at University of Cambridge, retweeted the "highly offensive" post from Oliver Rawlings, who has 243 followers on the social networking site, yesterday.
In his tweet Mr Rawlings called Ms Beard a "filthy old slut" and made a sexual comment.
He also addressed Jeremy Vine, asking the BBC Radio 2 presenter if he should be arrested over the remark.
Fellow users responded by condemning Mr Rawlings and within minutes he responded: "I sincerely apologise for my trolling. I was wrong and very rude. Hope this can be forgotten and forgiven."
He later added: "I feel this had been a good lesson for me. Thanks 4 showing me the error of my ways."
Ms Beard said exposing 'trolls' was the best tactic. Talking to a fellow user about her decision to highlight the abuse, she tweeted: "It is a tough call. I have increasingly opted for name and shame.
"It has to be outed. And maybe his friends can say 'stop'."