Johnny Vegas was advertising comedy on BBC Radio 4

The promotion for BBC Radio 4 comedy saw Vegas playing inside the fridge before the door was closed on him.

The BBC moved the trailer to after the 9pm watershed following complaints.

But media watchdog Ofcom still upheld the complaints, ruling that adverts which could be imitated by children should not be shown before 9pm.

It ruled: "We welcomed the BBC's action in removing this promotion from pre-watershed broadcasts.

"However, we would not expect material to be shown before the 9pm watershed which could be easily imitated by children and potentially harmful.

"Promotions come upon the audience without warning and, in this case, there was the added possibility that children may not initially understand the comic situation and be able to assess the action's potential for harm."

The BBC said it felt the situation was so unrealistic, and the comic purpose so plain, that it was extremely unlikely to prompt copycat actions.

But a spokesman for the Royal Society for the Prevention of Accidents said the trailer was potentially dangerous.

"There have been lethal accidents involving children in freezers," he said.