JEREMY Corbyn is confident but not complacent that he will be re-elected Labour leader this autumn as the party confirmed the electorate for the contest will be approaching 600,000 people.

As Mr Corbyn is set to launch his campaign, his spokesman said: “He is not complacent in any way but he was elected with a landslide a year ago and by a lot of measures his support has increased among Labour Party members and activists and supporters. There's every reason to think that he will be re-elected."

After the deadline for registered members passed at 5pm on Wednesday, the party confirmed it had received more than 180,000 applications during the 48-hour window.

The 183,541 who each paid £25 to get their vote could play a decisive role in the battle between Mr Corbyn and the sole challenger Owen Smith, the former shadow work and pensions secretary.

The contest is also open to those of the party's 380,000-plus members, who joined before January 12 as well as affiliated supporters from unions and other organisations.

This means the electorate is at least 560,000.

Mr Corbyn’s spokesman had said earlier that it was "reasonable to assume" the majority of the new registrations had come from supporters of the veteran left-winger.

Labour confirmed Mr Corbyn and Mr Smith would be the only two candidates on the ballot paper for the postal vote, which ends on September 24; the eve of the party’s annual conference.

By the deadline of 5pm on Wednesday, Mr Smith, the MP for Pontypridd, had secured the nominations of 162 Labour MPs - more than 70 per cent of the party's 230-strong representation in the House of Commons - as well as 10 MEPs. Among his nominators were former rival Angela Eagle, who withdrew from the race on Tuesday, and ex-leader Ed Miliband.

The ruling National Executive Committee decided that Mr Corbyn, as incumbent leader, was not required to meet the threshold of 51 nominations to stand.

The party is now undertaking a process of vetting the applications for duplicates or people who do not share Labour's values before ballot papers are sent out.

Meantime, Labour announced which of its frontbench team would shadow the secretaries of state for the newly created Whitehall departments for Brexit and International Trade.

Shadow foreign secretary Emily Thornberry is taking on additional duties for shadowing Brexit Secretary David Davis, while Barry Gardiner will add international trade to his energy brief within Labour's business team, shadowing Liam Fox.

The appointments add to the roster of Labour shadow cabinet ministers who are doing more than one job as Mr Corbyn is constrained in his choice by the fact that 172 of the party's 230 MPs have backed a vote of no confidence in him.

In a separate development, Mr Corbyn’s spokesman said the Labour leader had neither ruled out nor endorsed proposals for a second EU referendum after the Brexit negotiations were complete.

"That has to be dealt with later," he explained. "There needs to be some form of democratic accountability for what is negotiated. People voted in the referendum but didn't have a clear sense of what package was involved.

"But what form that accountability should take should be settled later," he added.

Earlier, Mr Smith insisted he had never supported part-privatisation of the NHS.

He was responding to attacks from Mr Corbyn's supporters, who branded him "Blair-lite"; the Welsh MP insisted he was committed to a free health service.

Opponents have pointed to his time as a lobbyist for drug firm Pfizer in 2005 when he reportedly said choice was a good thing in the NHS.

But Mr Smith said he had never used the word 'choice' to advocate part-privatisation.

“I have never advocated privatisation of the NHS," he declared, stressing how he believed in a “100 per cent publicly-owned NHS free at the point of use”.