Labour has secretly suspended 50 of its members over anti-Semitic and racist comments as officials struggle to cope with the crisis engulfing the party.
Senior sources reveal that Labour’s compliance unit has been swamped by the influx of hard-left supporters following Jeremy Corbyn’s election.
The suspensions that have been made public so far are said to be just the tip of the iceberg.
On Monday night Mr Corbyn appeared to acknowledge there was a problem for the first time, while insisting it was “not huge”. He told the Daily Mirror: “What there is is a very small number of people that have said things that they should not have done. We have therefore said they will be suspended and investigated.”
There is growing pressure on the Labour leader ahead of the local elections on Thursday, in which his party is forecast to lose more than 100 seats.
Senior figures are now so concerned about the row that they are openly discussing the possibility of an attempted coup following the EU referendum.
MPs are said to be plotting a coup to remove Mr Corbyn after the election if things go badly, with shadow chancellor John McDonnell poised to take over.
It prompted Mr McDonnell to issue an extraordinary denial of the claims on Monday night.
He said: “Media and right wing dirty tricks and lies trying to divide me and Jeremy. They should know it only unites us even more and makes us stronger.”
Also on Sunday night shadow education secretary Lucy Powell became the first shadow cabinet minister to acknowledge the party had a problem with anti-Semitism.
She told Channel 4 News : “There clearly is an issue with anti-Semitism in the Labour Party otherwise we wouldn’t have spent the best part of the last six or seven days talking about it.
“I think it is a very small element within the Labour Party and probably a small element in wider society as well. And that’s why we are taking swift action to root it out.”
On Monday it emerged that the party suspended three councillors within seven hours over a series of allegedly anti-Semitic posts on Twitter and Facebook.
Two of them had called for Israeli Jews to be relocated to America while a third compared a former Premier League footballer to Hitler.