The law of the jungle creates a bloodbath at 'News at Ten'

'It's like the last days of Pol Pot.' James Morrison reveals the inside story of the resignations and recriminations that have riven ITV's flagship news programme

Bong! ITN's political editor leaves after only three years in job. Bong! His female deputy quits in disgust at missing out on promotion. Bong! ITV News editor quits before he is pushed. Bong! Ratings plummet to all-time low.

News at Ten, ITV's flagship news programme, presented by Sir Trevor McDonald, is in turmoil. Sources linked to ITN have exposed a catalogue of in-fighting in the newsroom – and revealed it is on the brink of "meltdown".

Describing the day-to-day battle between rival factions, one recently departed ITN veteran told The Independent on Sunday: "It's like the last days of Pol Pot."

Others paint a picture of swingeing budget cuts, hellishly long working hours and power-crazed ITV executives who "second-guess" ITN news editors.

The revelations come after a week in which two key ITN players quit amid a flurry of claims and counter-claims. First over the fence was ITN's political editor, John Sergeant, who announced he was leaving to pursue "other broadcasting opportunities" and a career in writing. He was followed by Nigel Dacre, the editor of ITV News, who insiders say jumped before he was pushed.

While both Mr Sergeant and ITN insist he is leaving on amicable terms, sources say his colleagues have been frustrated at his "relaxed" attitude. The 58-year-old veteran is currently "on sabbatical" writing a biography of Baroness Thatcher.

Mr Dacre's departure comes after he was told he would not be promoted any further at ITN. The company's recently renegotiated ITV contract also makes it clear the network is seeking a new editor. Sources say the first Mr Dacre knew about last week's announcement concerning his "resignation" was when he arrived home from holiday on Monday.

As if all this wasn't bad enough, ITN's deputy political editor, Jo Andrews, is also leaving. Ms Andrews has not commented on her impending departure but sources say she is seething at her bosses' apparent intention to parachute James Mates, ITN's Washington correspondent, into Mr Sergeant's job over her head.

The looming crisis comes against a background of falling ratings for News at Ten, which now regularly attracts a million fewer viewers than BBC1's 10pm bulletin. One ITN stalwart who recently left in protest over issues including the alleged "dumbing-down" of the news agenda told the IoS: "ITN was the best television news organisation in the world. You would go anywhere and everyone would open their doors and say, 'Oh, ITN, come in.' That doesn't happen any more."

On one side of the struggle for the heart and mind of ITV News is the "old guard", represented by the likes of ITN's ex-political editor Michael Brunson and Sir David Nicholas, former editor-in-chief at News at Ten. On the other is a "new guard", led by an army of photogenic newsreaders such as Mary Nightingale, and directed, say critics, by ITV's forthright controller of news, Steve Anderson.

The friction between ITN and its ITV paymasters stems from the massive re-structuring the network has undergone over the past decade. Whereas ITN was once a virtual subset of ITV, the two are now entirely distinct, with the former providing separate news services for Channel Four and Channel Five. Since the reorganisation, there have been tensions over the extent to which ITV should dictate the precise nature and scope of the news coverage it "buys in". ITV insists ultimate editorial control remains with ITN but others take a different view. Referring to the allegedly fractious relationship between Mr Anderson and Mr Dacre, one source said: "He [Anderson] will second guess Dacre's running order all the time. It's driven Dacre nuts." Commenting on Mr Anderson's news priorities, he added: "He's only interested in celebrity nonsense."

Both ITV and ITN strenuously deny allegations of rifts or editorial interference. Mr Anderson denied dictating news agendas to ITN, but argued that, in the event of major breaking stories like the Soham tragedy, he wouldn't have been doing his job if he hadn't adopted a hands-on approach. Of Mr Dacre, he added: "We've worked together for four-and-a-half years. If there had been a real problem it would have manifested itself before now. He's been a fantastic editor for ITN."

Publicly, Mr Dacre is also closing ranks, praising the "strong newsroom" he has left behind, though it remains to be seen if The Daily Mail, edited by his brother, Paul, will do likewise. Mr Sergeant too insists his parting is amicable.

But ITN has influential critics, among them Gerald Kaufman, chairman of the House of Commons Culture, Media and Sport Select Committee. "I never watch it any more," he claims. "If I want to know what's going on, I go to Sky."

And finally ... one former ITN reporter predicts that, within five years, the battle for breaking news coverage will be a two-horse race between the BBC and Sky. ITV, he believes, will be reduced to little more than a populist entertainment channel. "It will cease to be a big hitter," he said. "The last two weeks have seen the beginning of the reading of the last rites."