The libel lawyer Mark Lewis is applying for a court order against the Labour Party on behalf of a client to force it to divulge who leaked the antisemitism report last April, so they can be sued.

The move, known as a Norwich Pharmacal Order, has previously been used against social media companies such as Twitter to get them supply the names of anonymous users.

It would protect Labour from facing action itself, provided the party did not sanction the leak.

But if it emerged they had authorised the leak of the report, the party could end up being sued.

Three names of individuals previously employed by the party have been mentioned to the JC in relation to the leaking of the report.

The JC understands that if, after a High Court hearing next week, Mr Lewis finds out who did leak the report, he will not be allowed to divulge this information.

But in the event of any future libel claims against those who did leak the report, their names would eventually come out in open court.

Next week’s High Court hearing, which begins on Monday, involves a former senior Labour staff member whose private messages were included in the leaked report.

The leaked dossier was an attempt to portray Labour staff who were opposed to then leader Jeremy Corbyn as having hindered efforts to tackle antisemitism.

The document- dated March 2020 and leaked in April 2020 - claimed some Labour Party staff did not want Mr Corbyn to win the 2017 general election.

The 860-page report included WhatsApp messages from named individuals, appearing to make derogatory comments about Mr Corbyn, party policy and the membership.

But it was leaked in an unredacted version – including the names and details of complaints made by Jewish members and non-members of the party about individual cases of alleged anti-Jewish racism.

The names, including those of Jewish members alleging serious wrongdoing, were widely circulated online, including on far-right websites.

Mr Lewis is representing numerous claimants over alleged breaches of data protection laws.

He refused to comment over next week’s legal move.