The director general of the BBC has defended the role of a senior manager who allegedly organised a string of celebrities to sign an open letter to David Cameron backing the corporation.
Danny Cohen, the BBC's director of television, faced calls to resign over allegations he had a hand in orchestrating a letter signed by Dame Judi Dench and Daniel Craig arguing that plans to reform the BBC would damage Britain.
Some 29 stars including JK Rowling and Sir David Attenborough also backed the letter, which warned that a "diminished BBC would simply mean a diminished Britain".
But one of the signatories, Radio 1's Annie Nightingale, said she had not read the letter and had been encouraged to put her name to it by her boss, who told her it was organised by Mr Cohen.
Questioned about it by MPs, Lord Hall, the director general of the BBC, said they had been "inundated" with offers by stars to go public in their backing of the broadcaster.
Chairman of the Culture, Media and Sport select committee Jesse Norman asked Lord Hall: "In July it was reported that one of your senior team Danny Cohen has been involved in lobbying stars to support a letter in favour of the BBC. Is this true?"
The director general replied: "He was involved. But the people who wanted to say what they said were the people whose voices counted.
"I don't want to be unhelpful here, but it's odd that people who want to support the BBC and the BBC they believe in and support, have been told they shouldn't be doing that. A lot of people want to support the BBC."
He said that for months a "wide variety of artists" offered to go public in their support for the corporation.
And he rebutted suggestions that Mr Cohen may have broken BBC editorial rules through his involvement, explaining that "we are allowed to speak about the BBC".
Mr Norman said the intervention amounted to getting "well known, much-loved national names" to pledge their support for the BBC.
The letter came as the future of the BBC, the licence fee and its breadth of programming is facing fundamental reform in light of cuts.
But Mr Norman said: "This is a direct attempt by proxy to influence a Government initiative and it includes a senior person on your team and another senior person which suggests an element of systemic involvement.
"I'm asking you why you don't agree with that and why you haven't had an inquiry."
He asked Lord Hall to write to the select committee and explain exactly who at the BBC was involved in organising the letter and whether they investigated the matter.
Rona Fairhead, chairwoman of the BBC Trust, said there was a "clear exemption" which meant the BBC could lobby on broadcasting issues.
She told the select committee: "There is a clear ability for the BBC to lobby for broadcasting issues. I think it's reasonable for any organisation to encourage its supporters to speak out on its behalf.
"And I think the BBC made clear that they were involved in that process - none of the public could be under the illusion there had not been some BBC participation."