Efforts by parents to monitor their children's use of the internet are being undermined by new "smart phones" which offer speedier online access than some home computers, an official report has said.
Although mothers and fathers want their children to have a mobile phone for safety and social reasons, they now realise it leaves them powerless to stop access to inappropriate internet sites, including pornography, the research has found.
Parents also worry that internet-ready mobile phones leave their offspring open to direct and inappropriate advertising.
Their fears were discovered by a review, Commercialisation and Sexualisation of Childhood, which is being carried out by the Mothers' Union for Sarah Teather, the children's minister.
The review is due out next month, It suggests that nine out of 10 parents think that their children are growing up too quickly because of increasing sexualisation and commercial pressures, mainly from the internet and television.
The review has found that direct advertising through mobile phones was the marketing tool that most angered parents, with more than a third — 35pc — believing it wrong. Products linked to social networking websites which invite children to click on them were second on the list of features to upset parents.
The review, conducted by Reg Bailey, the chief executive of Mothers' Union, a Christian charity, has also uncovered growing concerns about the exposure of children to sex on television.
In a poll of 1,000 parents, the review has found 41pc said that in the previous three months they had seen television programmes or advertisements before the 9pm watershed that they considered wrong for their children to view because of their sexual content.
40pc said they had seen window displays or advertising hoardings inappropriate for children.
Mr Bailey believes parents need to become far more aware of how quickly technology is changing and to realise that children are affected directly by adult attitudes to sex and money.
"Parents are telling us in no uncertain terms that they are worried about the pressures on children to grow up too quickly," he said. "It is clear that their concerns have not been created out of a moral panic but from their everyday experience.
"They are struggling against the slow creep of an increasingly commercial and sexualised culture and behaviour, which they say prevents them from parenting the way they want.
"Parents are disappointed that some of the existing regulation and self-regulation is starting to let them down.
"They feel that traditionally trusted controls like the television 'watershed' have become less rigorous and the lines have become more blurred.
"They are also uneasy about marketing to children through new digital media.
"They are particularly frustrated when sophisticated marketing techniques are used which they are unaware of and therefore unable to manage the pressure it creates."
Mr Bailey is unlikely to call for new legislation, but instead to argue that the process for parents to lodge complaints should be strengthened and simplified.
Parents concerns include:
* Children are growing up to quickly and behaving in an overtly sexual manner before they are old enough to really understand what sexually provocative behaviour means.
* Celebrity culture, adult style clothes and music videos are encouraging children to act older than they are.
* Lack of responsibility from business and government in allowing advertising to children.
* Too many clothes, toys, games, music videos or other products that are inappropriate for the age group they were aimed at.
* The use of phone and text adverts when promoting products for children.
* The increasing pressure to buy non-essential items for their children so they don’t feel left out.
* Public places (shop window displays, advertising hoardings) that they felt were inappropriate for children to see because of their sexual content.
* Programmes or adverts on TV before 9pm watershed that they felt were unsuitable or inappropriate for children due to their sexual content.
Telegraph Media Group Limited