The father of a teenage girl who killed herself after being abused by brutal bullies on a social networking site has called for it to be closed down.
Dave Smith said his 14 year-old daughter Hannah died on Friday in Lutterworth, Leicestershire, after being "cyber-bullied" on the question-and-answer website ask.fm, which allows users to send messages to one another without their identity being disclosed.
He is urging the authorities to close down the site, and those like it, after stumbling across cruel taunts from so-called "trolls" that he said drove his daughter to take her own life.
"How many more -teenagers will kill themselves because of online abuse before -something is done?
"These sick people are just able to go online and hide behind a mask of anonymity while they abuse vulnerable teenagers," he told the Daily Mirror.
"We've lost Hannah in the most horrendous way imaginable. It's time something was done so that no other family has to go through this."
The schoolgirl was found hanged in her bedroom by her sister Jo, 16. Mr Smith later found a note written by Hannah which read "I wonder if it's ever going to get better", the Mirror reported.
Hannah's stepmother Deborah Smith said she had shown no signs of the torment she was suffering.
"Hannah was bubbly, bright, cheerful and never had a glum face, " she told the Mirror. "There was no warning."
Mr Smith also urged parents not to allow their children to use the website.
Although people wanting to use ask.fm have to register an email address, name and date of birth, those posting messages can choose to do so anonymously.
Hannah's death echoes that of 16-year-old Jessica Laney, who was found dead at her home in Florida in December after users on social networking sites tormented her with insults and asked: "Can you kill yourself already?"
Laura Mckay from Skipton, writing on the Change.org petition set up in Jessica's memory, said: "I've been bullied on ask.fm and been told to kill myself many times. It's easy for people to hide behind and bully and it needs to be stopped."
Sharon Sully from Cumbria added: "How many more young lives have to be lost before it's (ask.fm) closed down?"
Philip Parsons from Southport wrote: "When does the freedom of the internet become a cancer that destroys lives? Websites like this need to be taken down immediately. The governments need to get serious about the cyber-bullying issues across the globe.
Another petition - available from https://submissions.epetitions.direct.gov.uk/petitions/48886 - also calls for greater measures to tackle websites like ask.fm.
It states: "Cyber-Bullying has been an ever increasing problem within the UK for a considerable amount of time with one of the biggest offenders becoming ask.fm, a site popular amongst young people where posts can be made with confidence anonymously which has led to bullying, mental health problems and suicides as well as grooming.
"The problem cannot be allowed to persist and whilst there is public opinion about digital rights please sign if you would like the Government to step in and insist that ask.fm and similar sites help us protect our young people. They are able to join from the age of 13 and can post anonymously. There is no option to block other users and only a basic 'report' button."
Emma-Jane Cross, from campaign group BeatBullying, said: "High-profile cases of trolling over the last week have deservedly received lots of attention in the media.
"However, we also cannot forget that thousands of young people, as in the tragic case of Hannah Smith, face a daily barrage of online abuse, death threats and harassment.
"Although they may not be in the public eye or have celebrity status, it's shocking that one in three young people are cyberbullied, and one in 13 face persistent abuse online.
"We cannot stand by while innocent children lose their lives. Adults need to set an example for young people and we all have a responsibility to tackle this type of behaviour and keep our children safe.
"We want internet service providers, schools, Government and the police to come together and produce a UK anti-bullying strategy, to prove that this kind of behaviour will not be tolerated.
"We'd also urge any young person worried about cyber-bullying to visit BeatBullying.org for advice and support."