The party is currently engaged in a protracted legal wrangle with five former employees whom it has accused of leaking a controversial report into how antisemitism complaints were handled under the leadership of Jeremy Corbyn.

It can also be revealed that to date, Labour has spent almost £1.5m on the ongoing legal action, which is currently going through the High Court.

Court documents seen by Sky News also reveal that Labour expects to spend a further £868,000, which could take the party's own legal costs to the region of £2.4m.

It has previously been reported that the Labour Party could face a legal bill of between £3m and £4m if it loses the case and taking into account the combined costs for both sides.

Party sources have recently expressed concerns that such a costly legal case could dent the party's election fund, with one member of the party's ruling body, the National Executive Committee (NEC), telling The Guardian in August that costs were "spiralling out of control".

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The source said Labour should be "questioning this monumental waste of members' and affiliates' money pursuing what appears to be a pointless political vendetta".

"Candidates will be up in arms that we are gambling with the party finances needed to win their seats," they added. "We need to have a laser focus on getting the Tories out."

However, in September it was revealed that the party had secured a record level of funding between April and June this year, totalling almost £7.5m - just shy of the Tories £10m.

The latest figures show the party has received £11.9m in donations so far this year.

The revelations come just days before senior Labour figures and activists gather in Liverpool for the party's annual conference and when it enjoys a near 20-point lead over the Conservatives in the polls.

The court action against the five ex-employees - including Mr Corbyn's former chief of staff Karie Murphy and his former director of communications Seumas Milne - was triggered after an internal report into the party's handling of antisemitism complaints was leaked to the media in 2020.

The 860-page report contained a number of damaging claims, including that factional hostility towards Mr Corbyn contributed to "a litany of mistakes" that hindered the effective handling of complaints.

The investigation, which was completed in the last month of Mr Corbyn's leadership, claimed to have found "no evidence" of antisemitism complaints being treated differently to other forms of complaint, or of current or former staff being "motivated by antisemitic intent".

The report also contained thousands of private WhatsApp communications between former senior party officials that were often derogatory about Labour staff, members, and Corbyn-supporting MPs.

The party has accused the five former employees, which also include Georgie Robertson, Laura Murray and Harry Hayball, of leaking the confidential report to undermine the party, which they deny.

At a recent hearing in the High Court, the party requested that the trial be postponed until after the next general election, which is expected to be held in either the spring or autumn of next year and cannot be held any later than January 2025.

The five claim that the party's wish to postpone the case until February next year at the earliest "is in fact heavily influenced by a desire to avoid, during an election period, litigation which will bring the Labour Party into the public eye in ways it might find embarrassing or uncomfortable, but which it has chosen to bring".

Witness statements by Mr Hayball and Ms Robertson that were read out in court were critical of attempts to delay the trial, with the latter arguing that the legal proceedings had already put her life "on hold".

"I am very anxious that the longer I am out of work, and therefore the bigger the gap in my CV, the harder it will be to attain employment, especially in a competitive field, even once my name has been cleared of the Labour Party's serious allegations in these proceedings," her witness statement read.

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In response, the Labour Party's lawyers argued that the five could obtain "a major tactical advantage" if the trial date coincided with the general election.

"It would be unfair and wrong in principle to place the defendant [the Labour Party] in a position where it was required to prepare for and conduct a trial in this very complex and weighty litigation... whilst also having to perform its vital constitutional role of contesting a general election," they said.

"It cannot effectively do both of these things at the same time."

A Labour 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."