LABOUR’S new UK leader will be announced at a special conference on Saturday April 4, the party has announced.

The timetable for the contest to succeed Jeremy Corbyn was agreed at a meeting of the party's ruling National Executive Committee in London today.

It came as expectations rose that Ian Murray, Labour’s only Scottish MP, will launch his bid for the deputy leadership role tomorrow. The Edinburgh South MP has insisted the party needs a “strong Scottish anchor”.

A party spokeswoman said the postal ballot of members in the leadership contest will run from February 21 to April 2.

She said: "We are by far the largest political party in the UK with well over half a million members. We want as many of our members and supporters to take part, so it has been designed to be open, fair and democratic."

The announcement came as a row broke out over claims that pro-Corbyn supporters were seeking to change party rules to “embed” Corbynism.

Karie Murphy, Mr Corbyn's chief of staff, and Jennie Formby, the party’s General Secretary, were said to have drawn up changes to the party’s organisation in the wake of the general election result in which the Conservatives won a landslide 80-seat majority.

One senior party source told the PoliticsHome website that Ms Murphy and Ms Formby wanted to "burn the house down" before Mr Corbyn's successor was chosen while another said: "It’s a clear scorched earth policy and would mean irredeemable change for the party. They have no mandate or right to be getting rid of people they don't like."

Rebecca Long-Bailey, the Shadow Business Secretary, who is regarded as the favourite should she throw her hat in the ring, failed to take her seat on the NEC as she is a leadership candidate; her absence could suggest she is about to declare her candidacy.

Tom Watson, the former deputy leader, expressed concern at Ms Long Bailey becoming leader, describing her as the "continuity candidate".

Asked to name his least favourite candidate in the race, the ex-Midlands MP told Sky News: "The one that I worry about - but I don't know what she stands for - I mean, when I look at Rebecca Long-Bailey, she's really the continuity candidate.

"She sort of stands for Corbynism in its purest sense and that's perfectly legitimate but we have lost two elections with that play.

"But she hasn't said anything yet; as far as I know she has not formally announced and it might be that she chimes a different note in her opening bid and that she wants to take the party in a different direction and she's very candid about what went wrong," he added.

Meanwhile, Angela Rayner launched her bid for the deputy leadership, saying Labour must "win or die".

The Shadow Education Secretary told supporters in Stockport Labour’s electoral coalition was "broken" in the wake of the election defeat and called on them to support her friend, Ms Long Bailey, for the leadership; another indication perhaps the Salford MP is about to announce it.

Ms Rayner is the fourth MP to enter the deputy leadership contest with Richard Burgon, the Shadow Justice Secretary, Dawn Butler, the Shadow Equalities Secretary and Khalid Mahmood, the Shadow Europe Minister, all having already declared their intention to run.