Efforts to crack down on cyber stalking are being thwarted because internet service providers will not take action, according to victims' groups.
The Network for Surviving Stalking says the police, Home Office and Crown Prosecution Service (CPS) are doing their best to tackle the problem.
It says service providers have a moral responsibility to help prevent the abuse but are doing little about it.
However, providers have said there is little more they can do.
Groups that support victims of online harassment say those targeted can suffer from anything from low level abusive messages to orchestrated campaigns.
There are few statistics but, anecdotally, they say cyber stalking is a widespread and growing problem.
One victim, who did not want to be named, told the BBC she was subjected to abuse, insults and death threats from a stranger online over a five-year period. She described receiving up to 30 messages every day.
Her work meant she had to be contactable online but she never replied to the messages and continually blocked the sender. However, her stalker simply changed their profile and continued to track, abuse and threaten the woman and her family.
Describing her experience, she told the BBC: "There were messages that they were going to hire a hit man to come and get me [and] they were going to cut my throat - really obscene messages.
"I constantly reported it to the police. I didn't feel I had the same support that someone would have if they were stalked offline. It was very much 'turn the computer off, change your name online'. I felt the support wasn't there and that was what was more upsetting because I felt very trapped and nobody could help me at all."
The police say every force does now have a dedicated point of contact for harassment issues and the government says it is taking action.
The Home Office, police and CPS are set to begin work with charities on an anti-stalking strategy in the autumn.
Jennifer Perry of E-Victims.org called on the government to "set the agenda so that online harassment will be taken seriously, the police take it seriously and business is forced to act".
But the Network for Surviving Stalking says internet service providers are the missing link as they are refusing to take part in the initiative.
It says they have a moral and corporate responsibility to take part.
Alexis Bowater, of Network for Surviving Stalking, said: "We need the internet service providers to get on board they need to take moral and ethical and corporate responsibility for what is happening to the millions of customers that they make billions out of."
However, the Internet Service Providers Association (ISPA) says it is doing all it can about the abuse but it is not possible to police the internet in the way demanded by victims' groups.
James Blessing, of ISPA, says many people "assume that internet service providers can do more that they actually can", comparing expectations of them to "asking the police to put a speed camera on every stretch of road in the country".
He said: "Internet service providers are there to help charities and government to find solutions to this and we have been talking to them for many years. Unfortunately expectations from other parties seem to be a lot a higher than what is actually achievable in a technical and operational sense."
Paul Mutton, of online security firm Netcraft, told BBC Breakfast that computer users always have to be careful what personal details they make available on the internet.
"If you don't want people to find out information on you, don't put it on the internet," he said.
"ISPs can do a little bit to help out, by encouraging users to install anti-virus software, firewalls and such like, but ultimately if you put your information online you are relying on those websites to remain secure, and for their privacy settings not to expose that information to anyone.
"If in doubt, don't put the information online in the first place."