London (CNN) -- The suicide of a 14-year-old girl who was apparently targeted by online "trolls" has added fuel to calls in Britain for action to prevent abuse on social media, following outrage over rape and bomb threats made against women via Twitter.
Teenager Hannah Smith was found dead Friday at her home in Leicestershire. She hanged herself after she was bullied on the website Ask.fm, her father told UK media, having gone there to look for advice on the skin condition eczema.
And the nightmare is not over for her family. Her older sister, Jo, is quoted in the Daily Mirror newspaper Wednesday as saying that she is now herself the target of Internet trolls.
"I've just lost my sister and now I've got to deal with getting abuse myself," she told the newspaper.
"These trolls don't care what happened to Hannah or what we're going through, they just live in their sad little worlds. It's really upsetting. I'm struggling to cope with what's happened and don't need these trolls hounding me."
Nasty comments were also posted on a Facebook memorial page set up in Hannah's memory.
More than 10,000 people have signed an online petition calling on the government to act after Hannah's death.
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."
Ask.fm, a social networking and question-and-answer site, said the teenager's death was a "true tragedy."
"We would like to convey our deepest condolences to her family and friends. We have reached out to the Leicestershire police and would be happy to cooperate with their investigation in to the true circumstances of her suicide," it said in a statement.
"Ask.fm actively encourages our users and their parents to report any incidences of bullying, either by using the in-site reporting button, or via our contact page. All reports are read by our team of moderators to ensure that genuine concerns are heard and acted upon immediately -- and we always remove content reported to us that violates our Terms of Service."
Advice issued by the Child Exploitation and Online Protection Centre, run by police, warns that Ask.fm is not suitable for children and offers limited privacy.
"More often than not the anonymous nature of Ask.fm leads to exchanges of hate speech and cyberbullying. As such we would not recommend it as an appropriate online environment for children whether they are over 13 or not," it states.
It adds that users can block people who post offensive comments and can also disable their own account if they choose.
A spokeswoman for Leicestershire police said the teenager's death was subject to a coroner's inquest, so police could not yet investigate. An inquest is held in Britain when a death is sudden or unexplained.
Arrests made over threats
Police are already investigating the online rape threats made against feminist Caroline Criado-Perez and Labour Party politician Stella Creasy, as well as bomb threats directed at several women journalists.
London's Metropolitan Police said Wednesday that a 32-year-old man had been arrested in Bristol, southwest England, as part of an ongoing investigation into allegations relating to the reported rape threats.
Two men were also arrested last week in connection with the inquiry.
Andy Trotter of the Association of Chief Police Officers said police will act when threats are made, but they can't respond to all offensive comments posted.
"Reports of credible threats and communications made over social media that specifically target an individual and constitute harassment will be taken very seriously by the police and investigated," he said.
But, he added, "There are many grossly offensive, indecent and obscene comments made every day on social media that will not meet the threshold and where the police should not be involved. ... We would like to see social networks do more to take actions such as instantly suspend accounts where it might be appropriate."
Amid growing public anger over the threats made against women, Twitter announced Saturday that it had revised its rules on abusive behavior and was introducing an "in-tweet" button to report abuse.
CNN's Krsna Harilela contributed to this report.