An investigation into how a controversial internal report by Britain's Labour Party on the party's handling of antisemitism claims was leaked will be conducted swiftly, Labour sources have said.The Labour Party is currently being investigated by Britain's Equalities and Human Rights Commission (EHRC) over allegations of institutional antisemitism within its ranks under former leader Jeremy Corbyn. In response, the party put together a detailed 860-page report which was intended to be submitted as an annex to the EHRC's inquiry, which was completed in the last months of Corbyn's leadership. The report has proven explosive for the party as it alleges opposition to Corbyn's leadership within the party hampered efforts to adequately deal with charges of antisemitism. It included WhatsApp messages from named individuals who appear to make negative comments about Corbyn, the party's membership, and party policies. Following an intervention by Labour's lawyers, the report was never submitted to the EHRC. However, over the Easter weekend it was leaked to the press unredacted. Claiming breach of confidentiality, some of those named in the report are considering suing the party. Many of those named no longer work for Labour, the BBC has reported. Labour’s national executive committee (NEC) met last week for their first to be chaired by Labour leader Sir Kier Starmer. The new leader, who replaced Corbyn in early April, has promised an independent inquiry into the report's findings and how was leaked. The committee agreed that the inquiry should deliver its report by mid-July. Momentum, the grassroots campaign group set up to support Corbyn during his tenure, and which has several supporters on the NEC, said that Starmer had told those present that disciplinary action would be brought against anyone named in the report who was found to have broken party rules. “We welcome Keir Starmer’s commitment to disciplinary action,” a Momentum spokesperson told The Guardian. “Ordinary members would rightly face disciplinary action if they engaged in such activity, senior staff members should be held to even higher standards.”A Labour party spokesperson said: “The National Executive Committee has today agreed the terms of reference for the independent investigation into the circumstances, contents and release of an internal report.“The NEC will meet again in due course to agree the individuals who will be appointed to lead the investigation.”Starmer, who married into a Jewish family, has previously said that there is a massive problem with antisemitism within Labour. Antisemites within the ranks "have to be dealt with robustly and swiftly,” he said, adding “and there’s no reason they can’t be.” He has advocated swiftly ejecting anyone "being clearly antisemitic" from the Labour Party.The leaked report into Labour's dealing with antisemitism said there was an “abundant evidence of a hyper-factional atmosphere prevailing in party HQ in this period, which appears to have affected the expeditious and resolute handling of disciplinary complaints”.While suggesting that it might not be immediately clear why this is relevant, the report added: “many staff, including GLU [governance and legal unit] staff and senior staff with responsibility for managing and overseeing GLU, were bitterly opposed to the leadership of Jeremy Corbyn, and seem to have been demotivated, or largely interested in work that could advance a factional agenda”.It continued: “At its extreme, some employees seem to have taken a view that the worse things got for Labour the happier they would be, since this might expedite Jeremy Corbyn’s departure from office. Further, there is little evidence of strong management of procedures, workloads and priorities in HQ, which also impacted GLU’s work.”Labour MP Charlotte Nichols called for the report to be published in full, saying: “Jewish members have a right to know what has happened and to see the evidence.”But Ian Austin, a former MP who left Labour over antisemitism said the report was unreliable, tweeting: “In last days of Jeremy Corbyn’s leadership, Labour trawled through 10,000 emails and messages to produce a report into antisemitism that attempts to shield him and his supporters from any blame, and instead pin responsibility on whistleblowers and former members of staff."