The BBC is "killing itself", former Crimewatch presenter Nick Ross has said.
Speaking at the Edinburgh International Television Festival, he said the corporation needs to supplement the licence fee with other income.
Ross told a packed audience at a session called The BBC: Under Siege that he is pro-BBC and thinks it is fantastic, but added: "I believe that the BBC is frankly killing itself, very slowly, strangling itself."
He said he sees an organisation clinging to a system where it will have to "fight" to survive every year or every 10 years, and will only get "more and more diminished".
Ross said the BBC depends on politicians and it needs to go out and supplement itself "much more aggressively".
Meanwhile, at the same session, director of strategy and digital at the BBC, James Purnell, said the corporation welcomed what Culture Secretary John Whittingdale said on Wednesday about how he has "never suggested dismantling the BBC".
Purnell said: "We very much welcome what John said yesterday."
He said the BBC welcomes debate about its future but said it is absolutely appropriate that if it is felt there is a danger of a "diminishing" of the BBC, that they address it.
Purnell said of Mr Whittingdale's comments: "I think he's changed the mood around the debate, very much so."
Whittingdale also said on Wednesday that suggestions that there was an ideological Tory drive to destroy the corporation were "just extraordinary".
The Culture Secretary had sparked concern among some supporters of the corporation after saying that a review of the BBC's royal charter would look at whether the broadcaster should continue to be "all things to all people" or have a more "precisely targeted" mission.