Online bullying doubles in a year
The number of children being bullied on the internet has doubled this year, with more than one in three now victims, research suggests.
In a poll of 11 to 17-year-olds, 35% reported that they have experienced cyber-bullying - compared with 16% last year.
Four in 10 said they had witnessed others being picked on online - almost double the 22% recorded last year.
The study also suggests that thousands of teenagers, including many aged 15 or under, are using messaging service Snapchat and dating app Tinder every day.
Some parents even helped set their children up with accounts, prompting fears that they are unwittingly putting them at risk.
Internet security firm McAfee polled 2,000 UK children and 2,000 adults with at least one child aged under 18 ahead of the start of Anti-Bullying Week on Monday, and compared the findings with a similar study carried out last year.
The research indicated that there is a more relaxed attitude among increasing numbers of parents regarding the risks posed online.
Less than a third of parents (27%) said they were worried about their child being the victim of cyber-bullying this year - almost halving from 45% in the previous year, while two-thirds (67%) of children are now allowed to go online without supervision - up from 53%.
However, more than three-quarters (77%) of mothers and fathers polled said they had conversations about online safety, up from 68% last year.
Andy Phippen, professor of social responsibility in IT at Plymouth University, said: " The responses from McAfee's survey shows that there is a real gap between parental concern and the reality of what children face online.
"While it is encouraging to see that these conversations are happening, there are areas in which parents may not be completely aware of their children's online behaviour.
"It's now time for parents to take the conversations to the next level and become further educated on the social platforms that exist, what ages they are suited for and what type of behaviour they encourage.
"Cyber-bullying happens across all platforms and children's use of social media is transient."
Around one in six of (17%) of the youngsters polled reported using Tinder every day, with almost half of those (46%) aged 15 and under.
The service was more popular among girls than boys, with one in five female respondents using it compared with 15% of males.
Tinder users are shown other subscribers close to their location and must give a positive reaction to them in the form of a tick, and receive one back in order to start communicating.
It is open to those who are 13 or older, with under-18s only able to match with people in the same age bracket.
Prof Phippen said: "It is very concerning to see the proportion of younger teens using apps like Tinder, whose aim is essentially hook-ups and dating, and very much for an adult audience.
"These apps also share location-based information and can be used as platforms for grooming and abuse."
More than a third (37%) of children polled reported spending up to 10 hours on Snapchat a day.
Reports recently emerged that explicit images taken with the app were intercepted by a third party app and leaked online.
Prof Phippen said: "Social platforms like Snapchat are becoming more and more popular with kids and children may not realise the risks of exposure they face."
One per cent of parents admitted helping set up Tinder profiles for their children, while nearly one in 10 (9%) gave them a hand joining Snapchat.
The research did not specify the ages of the children whose parents helped set up accounts, other than that they were under 18.
Samantha Humphries-Swift, of McAfee, said: "As a mother myself, it is worrying to see that parents are setting up social profiles for their kids and, as a consequence, unknowingly putting them at risk online."
Last week a report from the Health Select Committee said MPs heard evidence that sexting, cyber-bullying and inappropriate online content has caused a direct increase in mental health problems in children, including stress and anxiety.
Claire Lilley, head of child safety online at the NSPCC, said cyber-bullying is a "huge concern".
She added: "The use of teen dating apps can expose children to contact by adults who have a sexual interest in them because the age controls are often inadequate.
"The 24-hour nature of the internet and devices children use means young people can feel like there's no escape, with them facing almost constant harassment which can leave them feeling increasingly desperate and isolated. Children may sometimes know the person contacting them online but they could also be targeted by someone using a fake or anonymous account.
"The NSPCC is deeply disturbed that sexual predators could use teen dating apps and websites to target young people. Some of these apps state that adults and children can't mix, but it's all too easy for children to say they are older, or for an adult to pretend to be younger.
"Young people we surveyed told us they'd been asked for sexually explicit images or videos by adults, despite making it clear that they were under 16."
A survey by the charity's ChildLine service earlier this year provided an insight into youngsters' use of dating apps and sites.
It found that nearly half of all children and young people think dating apps can be risky, while 29% feel they are unsafe.
A third of those who have used a dating site or app have been asked by someone they have met on a dating app to meet offline, with 38% of those going ahead with the meeting.
When telling an adult who had contacted them from a dating app that they were under 16, only 13% of adults terminated contact, the ChildLine poll found.
Justine Roberts, founder of the Mumsnet internet forum, said: "How children negotiate the internet is a particularly tricky parenting challenge as it's not one that most of us have experienced in our own childhoods, so sometimes it's hard to know just how concerned to be.
"But parents on Mumsnet don't seem complacent - there are loads of conversations about children's use of the internet, how much is too much and how to make children aware of the digital footprint they leave behind."
A spokeswoman for Tinder said: "You must have an official Facebook account in order to join Tinder.