Tony Hall - the chief executive of BBC news and current affairs and a front-runner to become the corporation's next director general - has written to The Guardian newspaper in response to comments made by Alastair Campbell at a Fabian Society seminar.

Mr Campbell, a former tabloid journalist, called on the BBC to turn away from an agenda set by national newspapers and allow "democratically-elected politicians to speak for themselves, free and unedited".

Broadcasters should divorce themselves from print media and set their own agenda, he said.

Tony Hall: BBC's independence makes it trusted

In his letter, Mr Hall, who attended the debate, said the spin doctor had "side-stepped the real issue".

He said: "Firstly, the interests of democracy and the interests of government are not the same thing.

"Of course there is a real opportunity now with continuous news channels, BBC Parliament and the Internet to give open access to live parliamentary debate.

"But audiences expect the BBC to ask the difficult questions.

"We should not forget that the BBC is trusted because of its independence from governments and proprietors - if you destroy that trust we're all in trouble."

Mr Hall went on to say that one of the strengths of broadcasting in the UK was the range of formats ranging from light to the serious more analytical programmes.

He said: "There's a role for both. But the quality of our national debate will suffer seriously if politicians embrace the light and chatty formats and eschew the more analytical.

"People do want to identify with politicians as 'real people' - but they also want to see them grilled about the hard choices they are making for us."

In his speech on Tuesday night, Mr Campbell said: "Live media is where the future is at. Radio 5, Sky, CNN, News 24, the Internet, burgeoning radio and TV.

"But turn on News 24 or 5Live for a round table and you'll hear a group of print journalists pontificating."

He added: "There is media-land and there is the real world.

"The BBC should be the bridge between the two."

He focused criticism on the BBC's political unit based at Millbank near Westminster, which he described as "a ghetto, a village where people are feeding off each other all the time".

Mr Campbell has made frequent attacks on the media - and in turn been attacked over his news management policies.