Senior Labour figures have interfered in the disciplinary process of dealing with accusations of anti-Semitism, ex-party officials have told the BBC's Panorama.
Seumas Milne, one of Jeremy Corbyn's closest aides, told officials the party was "muddling up political disputes with racism" and must review processes.
And General Secretary Jennie Formby attempted to interfere in who sat on a panel examining a high-profile case.
Labour said there was no interference.
Instead, it said the former staff making the claims were "disaffected".
But Sam Matthews, the party's former head of disputes, said he interpreted an e-mail sent by Mr Milne - the Labour leader's communications chief - in March 2018, calling for a review into how complaints were handled, as "an instruction".
Mr Matthews is one of eight former Labour officials - seven of whom worked in the party's Complaints and Disputes Department - who have spoken to Panorama about their experiences of dealing with anti-Semitism cases.
Four chose to talk publicly despite having signed non-disclosure agreements (NDAs) with Labour not to discuss any aspects of their work for the party.
Louise Withers Green, a former disputes officer, left the Labour Party after being signed off with depression and anxiety.
She had signed an NDA so she did not have to work her notice period, but despite that spoke to the programme, saying she wouldn't "be able to live with myself unless I speak up about the horrendous things that I know have been happening".