Sir David Attenborough has warned that the BBC is in "real danger" and he is "very concerned" about its future.
The naturalist said the threat of cuts as well as competition from rivals such as Netflix are "very real problems" and said if the BBC does not have the support of the public it is "lost".
The BBC's Royal Charter, due to expire in 2016, is currently under Government review, and Culture, Media and Sport Secretary John Whittingdale sparked fears the BBC would be scaled back when he said the review would look at whether the corporation should continue to be ''all things to all people'' or have a more ''precisely targeted'' mission.
Speaking about the future of the broadcaster, Sir David, 89, told reporters: "It's in real danger. And if you lose the BBC, I mean I certainly will have lost a very, very important element of my life. And I would like to think that quite a lot of people in Britain think the same thing. I certainly do.
"The BBC is an extraordinary organisation and it's got enough problems trying to keep up with changing social demands let alone what the politicians want to do with it, so I am very concerned about the future of the BBC."
Asked if the public should be wary of Mr Whittingdale, who has said there is ''no prospect'' of the BBC being abolished, Sir David said: "Yes. I mean the BBC depends upon the public ... if it doesn't have the support of the public the BBC is lost, but that doesn't mean to say that every 65 million, or whatever it is, living in this country, all of us think all the time the BBC is wonderful. No, but every section of society, for one reason or another, at some time or another ... should be glad that the BBC is there."
He added: "The BBC's not above government. The BBC is not above society. The BBC is part of society and it's not above the law and it's right and proper that the Government should, under certain circumstances, take action, and determine what the BBC should do or should not do. That is correct democratic procedure. But one of the things government should do is keep BBC at arm's length, or keep themselves at arm's length, because the power of the BBC is that it is at arm's length from the Government but it's not above the law."
Asked whether he thinks the BBC is wonderful all the time, he said: "No, of course I don't."
He added: "I know perfectly well it's impossible that the BBC should be absolutely wonderful all of the time. Of course it's not. No human organisation is. There are lots of things you can do better, there are lots of things you can do more economically, there are lots of things you can do more imaginatively, but by and large it's doing pretty well."
The BBC agreed to take over responsibility for funding TV licences for over-75s from the Government earlier this year.
A senior executive said in July the BBC will ask over-75s to opt back in to pay the licence fee to help fund the corporation.
Asked about paying for his TV licence, Sir David said: "If you're asking me have I said 'here's £150', the answer is no I haven't done. Maybe I should."
Sir David, who was talking ahead of his latest nature documentary about the Great Barrier Reef, said programmes such as The Hunt are an "international financial support" which make money.
"And it only does that by being the best. I can say that because my contribution is minimal. What makes it the best are the fantastic pictures that it has and which is meant that it's shown all over the world. And we can hope that this programme will do the same," he said.
:: Great Barrier Reef with David Attenborough will air at 9pm on December 30 on BBC One.