DOZENS of party members could be ineligible to vote in Labour's selection contest to replace disgraced MP Eric Joyce after fears were raised about how they joined up.

A Labour troubleshooter has told up to 90 new members in Falkirk they will only be permitted to take part in the ballot if they fill in a direct debit mandate.

Mr Joyce quit Labour last year after he pled guilty to four counts of assault in a House of Commons bar.

His departure means Labour must select a new candidate to stand in Falkirk for the 2015 General Election.

Three of the contenders are former council leader Linda Gow, digital communications expert Gregor Poynton and Karie Murphy, who is being heavily backed by the Unite trade union.

Unite's approach in the constituency has been under scrutiny after the union paid the postage for a "consultative survey" on whether an all-women shortlist should be used for the safe seat.

The consultation was suspended by the party after fears were expressed that the survey was flawed.

Eric Wilson, the UK party's senior constitutional officer, was then drafted in to sort out what one insider called a gigantic mess.

Scottish Labour has now intervened over the large number of new members who have joined the local party in Falkirk.

A report produced by a group inside Unite previously stated the union recruited "well over 100 Unite members" to the local constituency party last year.

Concern about the recruitment surge has been followed by Mr Wilson writing to new members who were signed up as far back as last summer.

He wrote: "There have been concerns raised about the considerable number of new members who have joined the local party since July 2012. There have also been questions raised about the validity of some of these new applications."

Mr Wilson also noted that the new membership subscriptions had been paid by either cash or cheque, but that "no continuous payment method" was processed at the same time.

He added that voting in the selection contest was conditional on the members completing a direct debit mandate for their second year.

The official concluded: "When concerns are raised with us we have to put in place appropriate procedures to guarantee the veracity of the membership."

A party source said that up to 90 of the members may have received a letter.

The source added that many, but not all, of the individuals contacted were part of the Unite sign-up.

Earlier this month, local party vice-chairman Richard Bryce resigned his post after citing division in the local party.

A Scottish Labour spokesperson said: "The Scottish Labour Party is taking steps to ensure an accurate and up-to-date list of eligible members who can participate in the candidate selection.

"We are confident in our procedures and that local members will be able to select the best candidate to represent the people of Falkirk in Westminster."