Broadcaster Baroness Bakewell has warned against growing threats to the BBC.
The Labour peer urged the Government not to cut the corporation "down to size".
Her comments came as she introduced a debate on the future of the BBC in the House of Lords.
Lady Bakewell criticised Chancellor George Osborne for saying that the BBC, like the rest of the public sector, should contribute to austerity and hit out at the agreement that the corporation would pay for free TV licences for over 75 year olds
She said: "The BBC is not part of the public sector like any other. It is an independent body set up and guaranteed by charter so it is wholly wrong for the Government to refer to it in those terms and load such an institution with what are cuts to its social services settlement.
"The BBC is under attack not from the public but from the Government of the day and vested media interests
"The BBC faces suggestions of a more fundamental change than we have ever seen.
"The Government seeks to instruct it on the type of programmes it should make.
"The scope and scale of programmes, it is suggested, should be of a narrower and more targeted range, possibly giving up its most popular formats - in other words it should be cut down to size."
She pointed to rising profits for other broadcasters such as Sky and ITV.
"The BBC's commercial rivals have spent more on the rights to Premiership football alone than the BBC spends on all its content," she said.
"And yet it is the BBC that the Government expects to make severe cuts. Why would any Government want to cut down such a success?"
She called for an extended period of public consultation on the next Royal Charter, which is up for renewal next year.
Tory former Cabinet minister Lord Fowler said: "I have never understood why some in this country refuse to take pride in a world-leading broadcasting organisation that is both British run and British owned.
"If you cross the Atlantic you find many American broadcasters who would give their eye teeth to have a system like this.
"I hope the Government recognise that the legacy that they have is a very proud one and a very great one and one that they must maintain."
Media entrepreneur Lord Alli also spoke out strongly for the BBC.
"It is an easy thing to make things smaller, to cut budgets, to stifle ambition, to retreat from the great challenges," he said.
"My vision for the BBC is a bigger BBC, a stronger BBC, a BBC that advocates our national interests and our national values at home and more than ever abroad too."
"It is only by being great at what it does and unapologetic for its size that we stand a great chance of passing a BBC on fit for generations to come."
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