The campaign to halt the "commercialisation of childhood" will seek funding from the Government for the new watchdog and is drawing up a charter of rights designed to protect children from being exploited by advertising.
The moves are planned by the pressure group Compass, which joined with churches and parents' organisations last autumn to demand protection for children, and raised the idea of a Swedish-style ban on all ads aimed at under-12s.
Neal Lawson, a former aide to Gordon Brown, who chairs Compass, said: "It's not just about banning and nannying. We are looking for positive examples of what can be done to help and protect children."
To sign up for Campaign's Action for Ads petition, go to brandrepublic.com/campaign.