Children could be able to access internet through 3G phones

The third generation mobiles, coming on the market later this year, allow users to access pictures on the web and use video messaging.

Some 73% of parents surveyed said they were concerned that "3G phones with internet access could threaten a child's safety".

Children's charity NCH questioned 624 parents with children under 15.

The charity is calling for every 3G handset used by under-18s to have filtering and screening software pre-installed so the young people cannot access pornography and other adult services.

The NOP poll, commissioned by NCH, showed 78% of parents said the technology would "make it more or less impossible to supervise and support children who use the Internet".

If they want these phones to take off in the youth market, they are going to have to convince a lot of parents that they are safe, or can be made safe John Carr NCH's internet adviser

Almost two-thirds (63%) of parents with children aged between 12 and 15 said their child knew more than they did about mobile phone technology.

NCH's internet adviser John Carr said: "NCH believes this throws down a major challenge to the mobile phone operators.

"If they want these phones to take off in the youth market, they are going to have to convince a lot of parents that they are safe, or can be made safe."

Overall, one in three parents said their child was more knowledgeable then them about mobile phones.

Numbers rose sharply with the age of the child, peaking at 77% of parents of 15-year-olds.

Japanese experience

The Association of Chief Police Officers said it was "well aware" of security issues and the threat to children.

The association spokesman and assistant chief constable of West Midlands Police, Stuart Hyde, said: "Police in the UK have been, and will continue to, work in close collaboration with the industry, law enforcement and other non-governmental organisations to ensure we are fully prepared to meet the challenges that this new "web in pocket" technology will create."

He recently visited Japan, where 3G mobiles have been in use on the mass domestic market for the past three years, as part of a small British delegation to explore issues surrounding their use and learn lessons from the authorities.

"This helped to identify several areas that need further analysis, research and action," he said.

Areas included preventing access to certain sites by internet service providers, establishing an age verification system and the possibility of government funding to "ensure an effective response to 3G criminality by UK law enforcement", he added.