SCOTTISH Labour has made urgent changes to the running of its leadership contest amid concerns about a mass sign-up of new members.

As revealed by the Herald, a number of recruits who became eligible to vote in the contest share an email address and mobile number, triggering fears about multiple ballots being sent to a single email account.

However, following a u-turn, any Labour member or supporter who shares an email address will now be issued with a postal vote.

A Scottish Labour spokesperson said: "The Procedures Committee has taken appropriate steps to ensure that everyone who has signed up for a vote and gone through the robust verification process has the opportunity to cast a ballot in the leadership election for their preferred candidate."

The contest between left-winger Richard Leonard and centrist Anas Sarwar has become bogged down in rows over who should get a vote in the race.

Leonard allies have recruited thousands of new affiliated “supporters” through the trade unions, a sign-up that has been questioned by the Sarwar team.

Sarwar backers have largely gone down the separate route of signing up a significant number of new members, a process that has also been subject to controversy.

To join online as a member, an individual was asked for postal and email addresses, as well as bank details for direct debit purposes.

However, while a very small portion of pre-contest members are believed to share email addresses, a much higher proportion of the new sign-ups have the same mobile and email.

A number of local constituency parties raised concerns about a pattern which, it was feared, could put obstacles in the way of verifying the new members.

Party insiders also felt uncomfortable about the prospect of more than one electronic ballot being accessed by a single account.

John Cork, who was the Secretary of the Glasgow Southside constituency party, was one official who contacted party headquarters after hundreds of new members were signed up.

He wrote to general secretary Brian Roy and highlighted individuals who share a mobile while being listed at different properties, but quit after his concerns were leaked to a newspaper.

Labour initially said that a postal ballot would be sent to everyone in instances where an email was shared by more than three people.

However, the party’s Procedures Committee has stepped in and ruled that any member or supporter - new, or existing - will be given a postal ballot if they share an email address.

Given that it is illegal to open another person’s mail, Labour believes this action will help protect the integrity of the ballot.

As a further measure, additional ‘spot checks’ are being carried out on members who share a common email.

A spokesman for the Scottish Conservatives said: “Labour’s leadership contest has been an absolute farce. Given the coups, briefings, plots and racism rows, it’s no wonder the party is seeking a root and branch review.”

A spokesperson for the Sarwar campaign said: "This is a matter for members of the Procedures Committee."

The Leonard campaign declined to comment.