Labour has spent more than half a million pounds as part of its lawsuit against five former staffers accused of leaking an internal report on antisemitism, the Guardian understands. The party has spent at least £503,260 in its bitter battle with ex-staff members, including Jeremy Corbyn’s former chief of staff, Karie Murphy, and his former director of communications, Seumas Milne. That sum is said to relate only to the total costs accrued for a recent hearing, that involved a failed attempt to gain access to Murphy’s private emails. The party has been refused permission to appeal. In total, the Labour party could face a legal bill of between £3m and £4m. In a high court order handed down this month, Mr Justice Chamberlain ordered the party to pay £90,000 as an interim contribution towards Murphy’s costs. Murphy, Milne and the three others – Georgie Robertson, Laura Murray and Harry Hayball – deny leaking the report by Labour’s governance and legal unit in April 2020. The report, titled The work of the Labour party’s governance and Legal Unit in Relation to Antisemitism, 2014–2019, was compiled in connection with an investigation by the equalities watchdog into allegations of antisemitism inside Labour. It leaked days after Keir Starmer became party leader. It included details of staffers’ private conversations expressing hostility towards Corbyn or his close allies and bemoaning Labour’s better-than-expected performance in the 2017 general election, and revealed instances of sexism and racism. Starmer supporters said it was leaked in an attempt to “smear whistleblowers” who had exposed antisemitism. The leak prompted those named in the report to launch legal action against the party for failing to protect their data, invasion of privacy and libel. Other legal costs incurred by Labour so far include £99,108 towards the five employees’ application for the lawsuit against them to be struck out, and £103,626 towards an anonymity application by the claimants in the case whose names were revealed in the report. Investigations by Martin Forde KC, the senior lawyer commissioned by Starmer to investigate the Labour party’s culture, the Information Commissioner’s Office and an independent external investigator, Morag Slater of CMP Resolutions, were unable to establish the source of the leak. Labour instigated the legal action against those accused of leaking the report in 2021, and it is understood that the substantive trial may not take place until the second half of 2024, possibly on the eve of a general election. A legal source with knowledge of the case said: “Labour will be facing a bill of several million by the time this saga ends and a media-fest airing Labour’s dirty laundry just before or during a general election.” With the trial expected to last at least two weeks, coupled with new revelations about the cost of the hearing, there are growing concerns among some in Labour that the lawsuit is racking up costs that could have been used for campaigning. A member of the ruling national executive committee (NEC) from the pro-Starmer wing said Labour should be “questioning this monumental waste of members’ and affiliates’ money pursuing what appears to be a pointless political vendetta”. They said: “The NEC has been kept in the dark about these costs, which are spiralling out of control. Candidates will be up in arms that we are gambling with the party finances needed to win their seats. We need to have a laser focus on getting the Tories out.” An insider has pointed to an increase in Labour’s income, primarily from donations, totalling £47.2m, which was 50% higher than the Conservatives received. A Labour party spokesperson said: “The party has conducted a wide-ranging and appropriately thorough investigation following the leak and is confident of the case it has presented to the court. That remains the case.”