SAN FRANCISCO — On Ask.fm, millions of American teens talk about their hookups, struggles to get good grades and wild weekend parties with no parents or adults to peer over their shoulders.
Some also use the social network to anonymously torment other teens.
With its popularity soaring in middle schools and high schools across the U.S., Ask.fm is coming under attack from parents, politicians and privacy watchdog groups. It has been linked to the suicides of four teens in Britain and Ireland and one in the United States.
Sandy Cowles, a former teacher and stay-at-home mother of three from Irvine, says her teenage daughter was bullied on Ask.fm, which lets users anonymously ask one another questions.
"People hide behind a computer screen, and there is no accountability whatsoever," Cowles said. "You think using Facebook is bad? For teens, this is a feeding frenzy in shark-infested waters without a cage. You have chum all over the place and you are dropped right in the middle."
On Monday, the Latvia-based operator of the website said it would make it easier to report online bullying and harassment. It also plans to let users opt out of receiving anonymous questions and will hire more staff — including a safety officer — to moderate comments on the site.
The pledge came as parents and politicians accused the website and others like it of not doing enough to prevent anonymous abuse of vulnerable teens.
British Prime Minister David Cameron has called on websites such as Ask.fm to "step up to the plate and show some responsibility."
The website, already hugely popular in Europe, entered the spotlight in the U.S. last week when 16-year-old Hannah Anderson, barely 48 hours after being rescued in the Idaho wilderness, logged on to Ask.fm using the name Hannahbanana722 to candidly share details of her ordeal.
In answering questions from Ask.fm users, Hannah, who had been kidnapped and held for six days, explained why she did not try to alert people she encountered on horseback that James Lee DiMaggio, 40, was holding her against her will. (She said she feared he would kill them.)
When asked whether she would have preferred that DiMaggio, who was shot and killed by FBI agents during the rescue operation, spend his life in prison instead, she wrote: "He deserved what he got." She has since deleted the account.
Hemanshu Nigam, chief executive of SSP Blue, an online safety consulting firm in Los Angeles, said teens are gravitating to Ask.fm in growing numbers.
"Middle school kids are picking up on it, and they are taking stuff they were doing on other sites and moving to Ask.fm because it's the new and cool thing right now," said Nigam, the former chief security officer of Myspace and a father of four. "What they are promoting is anonymity, and that allows people to ask really nasty questions or answer questions with really nasty answers. It's really digital bullying for the 21st century."
British authorities are investigating the deaths of two teens in recent weeks as possible cases of online bullying, urging parents and service providers to strictly monitor websites used by young people for abusive behavior.
One, Hannah Smith, committed suicide this month. The 14-year-old had received abusive messages from Ask.fm users such as "drink bleach," "go get cancer" and "go die."
Her father, David, told British television that he blamed his daughter's death on Ask.fm and on authorities for not monitoring such sites more carefully. He called for criminal charges to be filed against operators of the website.
"The websites and government are not doing enough, and certainly not quickly enough to regulate these sites," he said. "It needs to be done now, not in six months' time when another teenager might be dead."
Ask.fm, launched in 2010, is not the first social network accused of doing too little to shield teens. Advertisers fled Myspace as it faced criticism over a cyberbullying case. Facebook and its photo-sharing service Instagram also have fielded complaints from parents trying to protect children from online harassment.
The number of U.S. visitors to Ask.fm leaped to 6.3 million in July from 3.7 million in June, according to research firm ComScore Inc.
Like Instagram and messaging service Snapchat, teens have chosen Ask.fm as one of the ways they can spend time with friends — away from the prying eyes of parents and other adults.
Ask.fm has said that it has 57 million users in 150 countries and that it's adding new users at a rate of 200,000 a day. Half of its users are under the age of 18. Average visitors spend 100 minutes a month on Ask.fm, the company has said.
Maryland Atty. Gen. Douglas Gansler has urged advertisers to boycott Ask.fm. The site requires users to be at least 13, but younger kids lie about their age to use it.
In Europe, some of Ask.fm's most lucrative advertisers, including Vodafone, Save the Children and DialAFlight, a popular travel website, have pulled their accounts following Hannah Smith's death.
"This website is putting children at risk," Gansler wrote in an open letter to advertisers this spring. "A growing number of children under 13 use Ask.fm because it makes no meaningful effort to limit underage access, and these kids are being exposed to malicious anonymous postings, including racial slurs, sexual references, drug use and personal assaults."
In December, Jessica Laney, a 16-year-old from Florida, was found dead in her home after being bullied on Ask.fm. One user had asked, "can you kill yourself already?" Others had called her "fat" and "a loser."
In speaking to technology blog TechCrunch in July, Ask.fm Chief Executive and founder Ilja Terebin admitted that the rapid growth of Ask.fm had made it difficult for the company to "control everything."
Ask.fm is similar to Formspring, best known for being the "ask me anything" website where Anthony Weiner — using the screen name Carlos Danger — exchanged raunchy questions and answers with a 22-year-old woman.
Anonymity on the Formspring site gave cover to online bullies who used questions as a way to torment others. Ask.fm and Tumblr borrowed many of the now-shut site's features, and its appeal diminished. Cap Watkins, who used to work at Formspring, blamed the site's shutdown on consequences of the anonymity it had afforded its users. Two teens committed suicide after allegedly being bullied on the site.
Danielle Citron, a University of Maryland law professor and mother of two teens who is writing a book on online harassment, said she has kept a close eye on Formspring and Ask.fm, which she calls "Formspring on crack."
Despite the good intentions these services may have, giving teens the cover of anonymity can turn them into "awful tools for teens to torture each other," Citron said. That's one of the reasons she so carefully monitors her children's Internet and social media use.
Which is why she was so shocked to learn that her own 13-year-old daughter had asked a question on Ask.fm, although the girl had not joined the service.
Citron had a talk with her daughter, part of the dialogue that she says all parents must have with their kids about being safe online.
"Anonymity can bring out the best in us because we can be more truthful, but it can also bring out our worst impulses because we feel safe from consequences," she said.
Guynn reported from San Francisco and Stobart from London.