The idea is being seriously considered in Labour’s review of its policies and is the first concrete example of how the industry might be affected by Ed Miliband’s strategy to create "responsible capitalism".
The Labour leader is likely to be quizzed about the plan when he addresses Wacl on 27 June.
The Advertising Association will lead the fight against the proposal. A spokesman said: "Two government reviews since 2009, including one commissioned by the Labour Party, found that the commercial world has a great deal to offer young people. Responsible advertising to children, abiding by strict rules which in recent years have shown their adaptability, plays a hugely important role in allowing this world to flourish."
Ominously for the industry, the proposed ban has been floated by Jon Cruddas MP, who is in charge of drawing up ideas for the manifesto.