BBC's acting director general Tim Davie has vowed to "get a grip" at the corporation following the resignation of George Entwistle over a Newsnight broadcast on child abuse allegations.

Davie said he had set up a "clear line of command" in news. The director and deputy director of news have been asked to "step aside" pending an internal review into the way claims about former BBC presenter Jimmy Savile were handled.

Davie said Entwistle's pay-off was a matter for the BBC Trust. Davie was appointed to the role on Saturday after Entwistle announced he was resigning.

Entwistle left after eight weeks in the post with a year's salary of 450,000 pounds.

Amid criticism from Downing Street of the pay-off, Lord Patten, chairman of the BBC Trust - the corporation's governing body - has written to Commons culture, media and sport committee chairman John Whittingdale, describing the decision as "justified and necessary".

His letter says the sum was what the BBC would have had to pay if they had fired Entwistle and that the trust was considering sacking him if he had not volunteered his resignation.

Culture Secretary Maria Miller said it was "very difficult to justify the decision that's been taken. To really be able to justify to the licence fee payer value for money and this is going to have to happen".

Prime Minister David Cameron said Entwistle pay-off was "hard to justify". A Downing Street source said, "The Prime Minister thinks it's hard to justify."