The police are struggling to crack down on online abuse as the number of reported offences soars, a senior police officer has said.
The Metropolitan Police received 1,500 reports of online offences in London alone this year, deputy commissioner Craig Mackey said today.
He told the London Assembly that the issue has become a "bread and butter operation" for the force.
Mackey said that police are struggling to investigate the crimes as online trolls become better at hiding their identity.
"Increasingly there is a trend for the person targeting someone to use false IDs and profiles and increasingly to use software which disguises their IP address which provides some challenges in what we do," he told the London Assembly.
He said officers were also being frustrated by social media companies' reluctance to assist them.
"Most of the social media providers are based in the US which doesn't have the same privacy laws and as we know approaches freedom of speech in a different way," he said.
He added that it was often difficult to get the evidence to stand up in court.
"We need to provide screenshots from victims' digital media. It doesn't always provide the best evidence and we can later sometimes find some problems further down the line with the courts in trying to provenance things," he said.
Mackey said there had been a significant increase in reports of online bullying, harrassment, and violence without injury.
His comments follow a major online campaign to get social media companies to clamp down on online abuse.
A series of public figures including Labour MP Stella Creasy have spoken out after receiving death threats on Twitter.
The police were today urged to take the problem more seriously.
"This covers a growing area of online abuse and it's not just the celebs or the journalists or the MPs. If you go out and speak to colleges and schools you will find that this is one of the biggest issues that are being reported," Labour assembly member Jennette Arnold said today.
"This is not just young girls, it's young boys being bullied, being harassed, being blackmailed. Their lives are being made a misery."