The easy availability and extensive use of smartphones is exposing youngsters to pornography, a British study has warned.

According to research compiled by YouGov, an alarmingly large number of children, especially teenagers, are accessing inappropriate images and videos online on their smartphones. The study also noted that nearly  46 percent of parents have no idea about measures to protect their children's mobiles.

Among young mobile phone users, only 13 percent of them have security settings installed on their devices. The survey, which looked at the smartphone use pattern of British children aged between eight and 15, also found that 44 percent of them have restrictions accessing the Internet on their PCs.

Over the last four years, the number of children accessing videos online more than doubled from 15 percent to 36 percent, the research found. The number of youngsters accessing social networking sites on their mobile phones too has gone up from five percent to 38 percent during 2008-2012.

More than 21 percent of those surveyed have accessed adult content online on their smartphones, the survey noted. Many youngsters who spoke to the survey confessed to have accessed such content meant for adults.

The research also found that extensive use of smartphones has raised the level of cyber bullying among youngsters.