Mobile phones should be fitted with porn filters to stop children accessing inappropriate content from their handsets, says Professor Tanya Byron.
The government's internet safety advisor said phones that use a Wi-Fi connection to access the web posed the biggest threat, as kids can bypass any parental control set up on the phone.
Currently, parental controls can be activated either when the phone is purchased or by contacting a network's customer services department at a later date.
However Byron said many parents were unaware these controls existed.
Kids are using handsets with Wi-Fi connections, such as Apple's iPhone, to bypass parental controls
Instead, she suggested parental controls should be activated from the handset using a password.
In a two-year progress report for the UK Council for Child Internet Safety (UKCCIS), which was set-up in September 2008 following recommendations from Professor Byron, it was revealed that 13 percent of boys aged 13 to 15 had accessed websites with sexual content from their home internet connection.
"We have a huge number of under-aged children on social networking sites; we know that children who have Wi-Fi-enabled mobile phones can access the internet; we know that there are location-based devices; we know that there is an extraordinary ease of access to pornography for children and young people," Byron said.
"Speeding up, we need to see a code of practice for companies and providers, we need to really think about parental controls for mobile phones that can access the internet."
Byron also called for the government to implement new rules regarding video game classification.
"More young people are now accessing the internet on their mobile phones and games consoles, and as parents we need to manage the way our children are using these technologies," said Children's Secretary Ed Balls.
"I'm glad Professor Byron has made it clear that industry and government need to redouble their efforts to provide support to parents to help them keep their children safe online. We need to make sure we are constantly assessing progress against the rapid advancements in new technologies."
