This proposal comes in addition to suggestions from Cameron that include banning sexualised images in public advertising and covering up explicit magazine displays. The issues are set to be discussed imminently with retailers and advertisers in the hope of agreeing a new nationwide code of conduct that may be introduced for businesses.

Cameron also wants to stop under-16-year-olds becoming "brand ambassadors" in "peer to peer" marketing campaigns for toys and other goods.

The plans were revealed in a pre-Christmas letter ...