The BBC's Rachel Payne: Mr Dyke finally got a chance to answer his critics

Mr Dyke's appointment has provoked a furious reaction from the Conservative Party because of his past links with Labour.

Greg Dyke has a budget of £2bn to allocate

They say they are worried he will not be able to maintain the BBC's reputation for impartiality and fairness.

Mr Dyke said: "This is the most exciting job I can imagine. It's an enormous privilege to be asked to do it.

"If, like me, you have spent your adult life in broadcasting, you know that the BBC sets the standards which the rest of us try to follow.

'Labour cronyism'

"It is an outstanding journalistic and programme-making organisation. It has a reputation for honesty, fairness, and most of all independence, and I am determined to safeguard and protect that."

Greg Dyke: "This is the most exciting job I can imagine."

Prior to the last General Election, Mr Dyke gave £50,000 to Labour, but has now promised to sever his links with the party.

He told a news conference he had resigned from the Labour party and would be "scrupulously fair" in his new role.

Mr Dyke said he would strive to maintain the BBC's strengths of "diversity, quality and integrity" and enable the talent that was "packed" into the corporation.

Tory concern

In an earlier statement, the BBC governors said they were certain Mr Dyke would be determined to resist outside pressures from whatever source.

But Tory leader William Hague said: "Whilst respecting the right of the Governors to reach an independent decision, in the current climate of Labour cronyism, we are concerned that the appointment of Mr Dyke, who has given recent and substantial financial support to the Labour Party, may be prejudicial to the BBC's reputation and to its obligations in this regard under its Charter."

And Tory chairman Michael Ancram told BBC Radio 4's Today programme: "If there's any suggestion that there's bias towards the Labour Government at any stage, people will say of course there is because that's the leaning of the Director General.

"This is something which I think is bad for the BBC."

Tough decisions

Downing Street refused to get involved in the row, insisting it played no part in the appointment and saying it was a matter for the BBC Governors.

Liberal Democrat spokesman Nick Harvey also dismissed the row, saying: "They have seen the last two BBC chairmen appointed as well known active Conservatives.

"I would not say that either of these gentlemen have brought their politics to the job and I don't see why anyone would assume in advance that Greg Dyke would either."

Mr Dyke, a former London Weekend Television boss, now faces tough decisions on how to spend the BBC's £2bn annual budget.

He is previously known as a critic of the licence fee and a champion of popular entertainment and sports broadcasting.