A new study has revealed over three million UK families (42 per cent) have found their children looking at violent, sexually explicit, upsetting or inappropriate content on the internet.
Research conducted by uSwitch showed that 38 per cent of parents stumbled across their under-16s looking at content containing foul language, while 18 per cent came across violent or sexually explicit material.
In 17 per cent of cases, web content featured substance abuse, drugs, smoking or alcohol.
More than one in seven parents (14 per cent) have found their kids viewing material they consider 'upsetting' - such as graphic or disturbing news articles.
And in response, many have resorted to snooping to keep track of what their children are doing online.
Over half (56 per cent) of parents surveyed admitted to checking the internet history of their kids' devices, while 16 per cent have logged into their social media profiles.
Some 41 per cent have imposed bans on their children using live chat rooms, while 39 per cent have uploaded parental control software to try and block sites with explicit or unsuitable content.
But the reality is that many parents lack knowledge about the options available to them in terms of filtering content - despite broadband providers promoting such solutions.
Almost three-quarters (74 per cent) of parents could not name any parental control tools or software, and 42 per cent said they had never used them.
TalkTalk HomeSafe and Virgin Media’s Child Safe are among the options available for web filtering, allowing adults to monitor the sites their children are visiting and block inappropriate content.
Marie-Louise Abretti, telecoms expert at uSwitch.com, claimed a "staggering number" of children are exposed to inappropriate content online at "a worryingly young age".
"Nowadays, children not only have access to home computers, but also portable devices such as tablets and smartphones, so it’s far harder for parents to keep tabs on what their children are getting up to," she stated.
“However, it is possible to restrict what they can view. Simply having a device registered to a child user will stop them being able to access adult content."
Ms Abretti explained that parents can also turn off location services used by apps like Facebook, which stops other people being able to see where your child is.
She noted that schools, mobile networks and broadband providers all have a part to play in keeping children safe online. But parents agree they should take primary responsibility for their web-based welfare.
"Unfortunately, not all parents are clued up about the many different parental controls available that can filter inappropriate content and keep their kids safe," Ms Abretti stated.