Furious Labour supporters have taken to social media to complain they have been barred from voting in the leadership election.
More than 600,000 people applied to vote, apparently fuelled by the popularity of Jeremy Corbyn, with thousands attracted by having to pay just £3 to become "registered supporters".
But today many are bemoaning that they have received letters informing them they will not be entitled to vote, prompting the hashtag #LabourPurge. Labour is said to have prevented over 1,000 new sign-ups from voting in the election.
Letter received by writer Pete Sinclair
Against fears of "entryism" from members of hard-left parties and Tories attempting to sabotage the vote, the Labour Party has made clear it has a "robust" verification system to weed out members or supporters from rival political party parties.
But many on Twitter are confused why their vote has been rejected.
Have I Got News For You writer Peter Sinclair, who had his £3 application to join the Labour party rejected this morning, railed at an "outrageous attempt to subvert the democratic process".
He has written about why he was going to vote for Jeremy Corbyn. He admits voting for the Green Party in after abandoning Labour in 2005 following Tony Blair's "illegal invasion" of Iraq.
Meanwhile, reports have suggested a Labour committee ignored legal advice to add an extra layer of protection against "entryists" to the leadership race.
Lawyers told the party's procedure committee to double check new sign-ups known to have voted for other parties, in order to avoid legal attacks if the voter hopefuls were then rejected.
It was suggested suspects should have been asked to confirm they really did support the party's "aims and values".
The move would have allowed Labour to argue its voting system was “robust”, according to leaked minutes of a meeting last week seen by the Guardian, but the committee voted against the plan.
The Labour Party has said it will bar those who do not support the Labour Party’s aims and values, or have been excluded from the party in the past.
Some on Twitter pointed out the move fell short of representing a "purge".
And there might be good reason for their exclusion.
A Labour spokesman said: “The Labour Party has a robust system to prevent fraudulent or malicious applications.
"All applications to join the Labour Party as a member, affiliate or supporter are verified and those who are identified by our verification team as being candidates, members or supporters of another political party will be denied a vote.”