Labour is facing financial ruin as antisemitism whistleblowers and complainants have threatened to sue the party after an internal report containing their identities was leaked to the press.

Over a dozen people are reportedly preparing to sue the party under the Data Protection Act, with claims of breach of confidence, invasion of privacy, and libel. Senior Labour officials, who were already expecting a hefty fine from the Information Commissioner over the incident, are now bracing for an economic hit that could “bankrupt” the party.

“The compensation and legal bill could be enormous, from £3million to £8million. It partly depends how Sir Keir, who has to clean up his mess, reacts,” a source close to the complainants told the Daily Mail.

“That sort of legal bill would just bankrupt the party.. [the party general secretary] warned party members that anyone sharing the report ‘on an unauthorised basis will be immediately exposing themselves to potential significant civil and criminal liability’,” an MP told the newspaper.

The 860-page internal report was leaked in full to the media earlier this month. The report, which covered the party’s actions between 2014 and 2019, contained the names of people within the party that spoke out against antisemitism within Labour.

It is believed that the report was leaked to the press by loyalists to the former far-left leader of the party, Jeremy Corbyn, as the report attempted to shift blame away from the ageing socialist, claiming that factionalism had prevented the party’s leader from rooting out the borderline “neo-nazis” within the party.

Following the leak, the party moved to scrub the identities of the people mentioned in the report. However, the damage had already been done, with complainants claiming that they have been subject to online abuse and have received death threats since their names were leaked.

“It is a very lengthy report that mentions a lot of people. I’ve been contacted by 15 people. Each one of them could well have several claims. What is going on is phenomenal. It’s a bit like the soldiers leaving a barracks that they have to desert and setting it on fire,” attorney Mark Lewis told The Observer.

“For four years, people in Labour have said there is no antisemitism in the party, it’s just a smear. Now they say that of course there was antisemitism, ‘but it just wasn’t us’. They have not noticed the absurdity of their change of position,” Lewis added.

“There are actions against the party, actions against individuals, actions against commentators. People need to be careful about statements that have been made. If this bankrupts the Labour party or individuals, so be it. Actions have consequences,” he concluded.

Follow Kurt on Twitter at @KurtZindulka