A leading figure on Scottish Labour’s governing body has raised concerns about a surge of new membership applications in Glasgow during the leadership contest.

Stephen Low expressed fears to the party about new members allegedly sharing email addresses and phone numbers and called for some of the sign-ups to be deprived of a ballot paper in the contest.

In these cases, he said a ballot should be withheld from these individuals until they provided “written confirmation” that they “know they are a Labour party member”.

The memberships questioned by Mr Low are in Glasgow Southside, which is the local party of leadership candidate Anas Sarwar.

However, there is no suggestion of wrongdoing by Mr Sarwar or anyone acting for him.

A spokesman for Mr Sarwar said: “It’s incredibly encouraging that people across Scotland have joined the Labour Party and we are confident that many have been enthused to do so by Anas’s positive campaign and by a belief that he can be the next Labour First Minister.”

A source close to the Sarwar camp dismissed Mr Low's claims.

The battle between Mr Sarwar and left-winger Richard Leonard has become mired in rows over the size of the electorate in the contest, after the party used the race as a recruitment drive.

Mr Leonard’s supporters are believed to have signed up a huge number of trade union supporters in the last few weeks, while Mr Sarwar’s backers have recruited a sizeable amount of party members over the same period.

The Glasgow Southside local party, which is Mr Sarwar’s home patch, had around 700 members last year, but hundreds more individuals are believed to have signed up since the contest began.

John Cork, who was Secretary of the local party, flagged up concerns to party headquarters recently about some new Southside members, including people who he said share a mobile phone but are listed at different properties.

Mr Cork also highlighted concerns about fourteen new members signing up with an identical business email address, but he quit his post after his misgivings were leaked the press.

Mr Low supports Mr Leonard but had to leave the candidate’s media team after using an offensive word about a Labour MSP in a press statement. He represents party members on Labour’s governing Scottish Executive committee (SEC).

In an email to general secretary Brian Roy, Mr Low picked up on the memberships highlighted by Mr Cork: “I note your [Roy] point that signatures and bank details are checked. Again less than entirely reassuring when you can join online without providing a signature….”

Mr Low wrote it is “indeed the case” that married couples can share an email, but said “no child leaves school without an email address these days”.

He also claimed it “strains the bound of credulity” that, at one property in Glasgow Southside, a large number of adult residents have only “one mobile phone & email address between them”.

Mr Low added: “In that particular case they have more cars than that in the drive way.”

He continued: “Frankly I don’t think the vast bulk of the people on this list should be issued ballot papers without the Party receiving written confirmation from each individual that they know they are a Labour Party member.”

A Scottish Labour spokesperson said the party did not comment on leaked correspondence, but said: “The party has a robust process in place to ensure verification of new members and registered supporters.”

Mr Low said to the Herald: "Any implication by you that I have been involved in you having access to this email - or that I approve of you quoting my private correspondence will be a deliberate act of deception on your part."

The Leonard campaign did not comment.