The restrictions, which took effect on September 17th, are part of a wider effort to tackle childhood obesity and will ban the use of celebrities and licensed characters in radio adverts aimed at children under the age of 16.
In addition, promotional offers for junk food items will be banned, as will the use of nutritional and health claims.
The restrictions will join existing controls on television advertising and Andrew Brown, chairman of the Broadcast Committee of Advertising Practice (BCAP), described the move as "a significant milestone".
"The advertising industry has responded to government and public concern about rising levels of childhood obesity and demonstrated its commitment to playing its part in tackling the problem through the formulation of stringent advertising rules," he stated.
Existing campaigns have until December 16th 2007 to show compliance with the new rules.