More than a third of stalking victims are now targeted online as the internet leaves them with nowhere to hide, according to a major new study.
A poll found nearly one in five British women (18.1%) and one in 12 men (7.7%) have suffered repeated and unwanted contact or intrusive behaviour which causes them fear or distress.
Among those, 36.8% were stalked using online methods, research commissioned by the Suzy Lamplugh Trust showed.
The charity said survey respondents who suggested they had been "cyber-stalked" indicated a range of social media and web platforms were used by stalkers including email, Facebook, Twitter, dating websites and apps, WhatsApp, Pinterest, Instagram, Tumblr, Flickr and Snapchat.
Victims are being driven to disconnect from the internet by their tormentors, with the survey showing that more than a fifth (22%) of all those who had been stalked have withdrawn from some form of online activity or social media.
Experts said the findings highlight how cyber space has given perpetrators a new weapon in their armoury.
Forensic psychiatrist Dr David James, who worked on the study, said: "New methods of communication mean stalking online is something you can never get away from.
"In effect, you carry the stalker 'in your pocket' in the form of any mobile phone. This can be especially traumatising for victims."
The report - based on a poll of 4,054 British adults - also found:
:: Of those that have been stalked, 18.8% of cases lasted more than a year and 7.9% lasted more than five years.
:: More than a fifth (22.8%) of stalking cases involved ex-partners, 22.5% strangers, 17.4% acquaintances, 10.1% former friends, 8.1% work colleagues and 6.4% family members.
:: Over a quarter of victims (28.3%) felt concerned about going out in public and 20.4% reduced their social outings, while 18.6% changed their phone number, one in 10 (9.5%) moved home and 8.7% increased security at home or work.
:: Where online activity was the sole form of stalking behaviour, only 9.8% of victims reported it to the police.
:: People between the ages of 18 and 34 are significantly more likely to have been stalked online.
:: Of all stalking cases, only one in four (26.6%) have been reported to police, with nearly half (43.4%) of those who did report their experiences finding the response "not very helpful" or "not helpful at all".
Rachel Griffin, director of the Suzy Lamplugh Trust, said: "It is incredibly important that we are aware that victims of stalking can be harassed and abused both when they are going about their daily lives and when they are online."
Last year the Government set out proposals for new protection orders for victims of "stranger stalking" amid fears the internet is fuelling an increase in cases.
Twitter declined to comment. Under the microblogging site's rules, accounts responsible for harassment of others can be temporarily locked or permanently suspended.