Women who have received rape and death threats on Twitter say the Met have been slow to bring the culprits to justice.
The issue hit the headlines this summer when prominent women including Labour MP Stella Creasy, the TV historian Mary Beard and journalist Caroline Criado-Perez were targeted by so-called trolls on the micro-blogging site.
Threats of rape and other misogynistic messages prompted Ms Criado-Perez, who campaigned for the Bank of England to feature a woman on the back of the £10 note, to quit Twitter temporarily.
Three men aged 21, 25 and 32 were arrested this summer and bailed until the middle of October.
Ms Criado-Perez – who says she was sent another rape threat within 24 hours of rejoining Twitter – says the police are dragging their feet and failing to show enough sympathy for victims.
She told Channel 4 News: “I got asked to go back thorugh the tweets that I received, which were really graphic rape and death threats, to relive the experience to look for certain handles.
“In the event it seems that wouldn’t have been necessary anyway but I think that sort of points again to the way the police don’t have a firm grip on these types of crimes, how they might affect a victim.”
The Met told say they have looked at hundreds of tweets in the course of their investigation, but must focus on what they believe is a crime.
And the force is struggling to cope with soaring reports of online bullying and harassment, with around 1,500 additional offences recorded in a year.
Ms Creasy said Twitter need to start helping the police more.
She said: “It’s not a one-off what happened to me. Indeed the number of increasing reports show that we do need new protocols between the police and the technology companies, and we’ve got to push them to put them in place.”
Ms Criado-Perez said: “Twitter has taken some positive steps on the path to becoming a responsible platform that can provide freedom of speech for all, rather than just those who shout the nastiest and loudest. But they have so far completely refused to engage on the topic of their inadequate blocking system.
“Twitter claims that their system is best, because it’s not immediately obvious when you have been blocked. They are following the adage of ‘don’t feed the trolls’ – if you’ve blocked trolls they know they’ve won.
“But victims of harassment and stalking are telling twitter that this system is leaving them as the impotent targets of sustained orchestrated campaigns of harassment, with concerted trolls stalking the timelines of their victims and inciting their followers to continue to attack a victim.
“It also enables stalkers to continue to easily keep tabs on, and fixate on, their subject.”
Twitter has made it easier to instantly report abuse but lawyers say gathering evidence for a prosecution is hard work.
Media lawyer Jonathan Coad from Lewis Silkin said: “You’ve got to indentify the tweeter, which means going to a US judge and getting the information out of Twitter.
“And you’ve got to persuade a British court that it was obscene rather than socially acceptable. Putting those two together sometimes makes it a challenge to get a conviction.
“I think the biggest problem is society has to make up its mind about what is or isn’t acceptable as a tweet and that’s a real challenge “
Mary Beard is in the rare position of having received a personal apology from the young man who abused her online.
She declined to reveal what the repentant troll actually said to her, saying: “I’m not going to talk about that because it was absolutely private.
“But people always said on the radio: ‘What would you do?’ and I said: ‘Take him out for a drink and smack his bottom.’ He totally fully apologized and in fact he bought me lunch.”
She added: “Somebody comes up to me in a pub and says they’re going to kill me and do all the other particularly vile things, you know. I say ‘excuse me’ to the landlord, ‘Can you ask this man to leave?’ Now in some ways we’re going to have to work towards a way in which those kind of conventions are understood.”