More than two in five (21 percent) of 8 to 15 year olds in the UK have accessed inappropriate content from their mobile phone says the Carphone Warehouse.

Research conducted by YouGov on behalf of the mobile phone retailer revealed that this rises to a third of 14 to 15 year olds, although it's not always intentional and while some kids do go looking for adult content, many simply stumble across it.

The Carphone Warehouse said 2.8 million children in the UK own a smartphone, but only 13 percent of UK kids have security settings installed on their handsets. It appears that while 44 percent say they have parental controls in place on their home PC/laptop and 84 percent also have anti-virus software installed on their computer, the same care isn't applied to smartphones. Nearly half (46 percent) of parents said they are unaware parental controls for mobile phones exist.

The number of children watching online videos on their mobile phones has more than doubled since 2008, rising from 15 percent to 36 percent. Accessing social network from mobile phones has also surged from five percent in 2008 to 38 percent in 2011. The Carphone Warehouse says this makes it the second most popular online mobile activity, behind playing games cited by 73 percent of UK children.

However, cyber bullying via mobile phones is also a concern, with 12 percent of 8 to 15 year olds saying they've been a victim and six percent admitting to being the perpetrator. More than a quarter (27 percent) of UK kids said they'd received unwanted calls or messages on their phone and 18 percent of these were so concerned they told an adult about the unwanted contact.

The mobile phone retailer has joined forces with Professor Tanya Bryon, who has been advising the Government on child internet safety since 2007, to develop a free advice booklet for parents offering advice and tips on the latest software and security, as well as how to communicate with their children about their internet.

"With a digital divide existing between generations, and with only 13 percent of children having the correct parental restrictions installed on their phone, it's important we enable parents to support, educate and, as necessary, protect their children," said Byron

"This can be done by ensuring their mobile phone use is responsible, safe and as secure as possible. It is also important parents develop an honest communication with their children so that they can support them to be responsible digital citizens and help them with any worries or concerns that should arise."

Andrew Harrison, CEO of Carphone Warehouse, added the retailer wants "to help UK parents feel confident to know how to help keep their child safe while using the latest mobile phones".

The booklet will be available for free from 8th February at all 800 Carphone Warehouse stores nationwide. Alternatively visit the retailer's dedicated website for more information.