CIVIL war is inevitable in Jeremy Corbyn’s Labour Party, a former Foreign Office Minister has warned, as the pressure intensifies in the run-up to next week's crunch conference vote on scrapping Trident.

Kim Howells, who served in both the Blair and Brown administrations, made his remarks as Mr Corbyn made clear that if delegates in Brighton backed the proposal, then abolishing Britain's nuclear deterrent would become official party policy.

Mr Corbyn has spent much of this week behind closed doors at Labour’s HQ and his new Leader of the Opposition’s office in the House of Commons, putting the finishing touches to his conference agenda, including his all-important first set-piece speech next Tuesday.

But as the party continues to come to terms with a leftward lurch, Mr Howells hit out, saying that a “bunch of old Trotskyites” was never going to win power.

Speaking to BBC Wales Mr Howells made clear that, if he had still been an MP, he would have been “bitterly opposed” to the Corbyn leadership.

"I'd be saying things that I believe about the need to win political power and a bunch of old Trotskyites are not going win political power," declared Mr Howells.

Urging Labour MPs to consider whether or not Mr Corbyn could become Prime Minister, the former Pontypridd MP said: "There is going to be a civil war inside the Parliamentary Labour Party; it's nothing new, it's happened in the past.

"So the party's got to make its mind up; does it really think it's going to win again in the future with Corbyn as the leader? I don't think so."

But after Tom Watson, the deputy leader, urged his colleagues earlier this week to accept Mr Corbyn’s mandate and stop sniping, Chris Bryant, the Shadow Leader of the Commons, stepped in and told Labour MPs to “listen carefully to what Jeremy is saying” before writing off their new leader.

"Don't listen to the wild accusations from people. Just listen carefully to what Jeremy is saying. We are taking about doing politics in a different way and heaven knows it needs a change. The Labour party has always been about change,” insisted Mr Bryant.

Meantime, in a pre-conference interview with the left-leaning New Statesman magazine, Mr Corbyn made clear that not only would a conference vote for abolishing Trident become party policy but also that, despite differing views from some of his frontbench team, Labour would oppose the UK Government’s welfare cap.

On Monday, it is expected that for the first time in years a debate and vote will take place on whether or not to scrap Trident. Motions put forward by local constituency parties as well as CND Labour are almost certain to be accepted on Sunday for debate the following day.

The issue is likely to encapsulate the policy divisions within the party as while Mr Corbyn strongly opposes the nuclear deterrent and its renewal, others, including his Shadow Defence team, supports it.

The vote at the UK conference in Brighton will now almost certainly mean the Trident issue will be debated at the Scottish conference next month. But it is thought that while Scottish Labour leader Kezia Dugdale supports Trident renewal, many of her colleagues do not. It is possible that each Labour conference opts for a different view.

Asked whether scrapping Trident would become party policy if conference voted for it next week, Mr Corbyn was unequivocal, telling the New Statesman: "Well, it would be, of course; because it would have been passed at conference."

The leader’s position on welfare has also showed up differences with his senior colleagues.

Owen Smith, the Shadow Work and Pensions Secretary, made clear opposition to the welfare cap was Mr Corbyn’s “personal” view rather than party policy while Lord Falconer, the Shadow Justice Secretary, described the cap as “sensible”.

But the Labour leader, asked about the party’s position, said: “It’s what I’ve put forward as leader and I’ve made that very clear…We will now oppose completely the Welfare Reform Bill.”

The legislation proposes to reduce the benefits cap from £26,000 to £23,000 in London and to £20,000 elsewhere.