Seumas Milne leaked an internal Labour Party report which appeared to exonerate Jeremy Corbyn from claims of anti-Semitism, the High Court has heard.
Labour accused five former staff members on Monday of leaking an internal report into anti-Jewish racism in an attempt to protect their former boss.
The staffers accused include Mr Milne, the former Labour leader’s spin doctor, and Karie Murphy, his former chief of staff.
Georgie Robertson, a former press officer, and Laura Murray, who ran Labour’s complaints unit, have been named by the party alongside Harry Hayball, a former aide.
The five are accused of leaking an internal report that was intended to be sent to the Equality and Human Rights Commission in response to accusations that Mr Corbyn’s party had botched the handling of anti-Semitism complaints.
The report alleged that opponents of Mr Corbyn had inhibited investigations into Labour members in an attempt to damage the former leader, because they hoped for him to be replaced sooner.
Staff members named in the report, which was never submitted to the Commission, have since sued the party for breach of confidence because of the leak.
A barrister representing one of the named staffers said she had been the victim of a “one-sided factional attack” by Corbynites.
On Monday, Labour filed documents to the High Court counter-accusing the former Corbynite staffers of leaking the report in an attempt to protect their former boss from criticism.
All five former employees strongly deny leaking the report.
In a statement issued by their lawyers, they said: “The individuals entirely reject these baseless claims. They did not leak the report. They fully co-operated with the Party’s investigation by an independent external investigator, and with the inquiry led by Martin Forde QC. They understand that neither of those investigations concluded that they were responsible.
“The Party has already acknowledged in court that it cannot be certain who leaked the report and that its “case” against them is circumstantial. But it is now trying to make them foot the bill for legal action brought against it.
“The Party should be focusing on the deeply troubling evidence contained with the leaked report, rather than trying to wrongly scapegoat and victimise former staff who documented it, and who have not been accused by either of the independent investigations.”
The Commission eventually concluded that Labour could have done more to tackle anti-Semitism among its membership “if the leadership had chosen to do so”.
It also said that the party had twice breached the Equality Act “by committing unlawful harassment” against Jewish people.
Mr Corbyn’s response to the Commission’s findings, in which he said claims of anti-Semitism had been “dramatically overstated for political reasons”, saw him kicked off the Labour benches.
The leaking of the report that blamed Mr Corbyn’s opponents for the failures in handling of cases has also been subject to a separate inquiry led by Martin Forde QC. His hotly anticipated conclusions have been delayed, but are expected to be released this year.
The Labour Party declined to comment.