Labour deputy leader Tom Watson has demanded that the party publishes its submission to an inquiry into anti-Semitism allegations.
He said he had a right to see documents handed to the Equality and Human Rights Commission (EHRC).
Writing to Labour’s general secretary, he also criticised the party’s response to claims on the BBC’s Panorama about its handling of anti-Semitism cases.
Labour has said claims in the programme were inaccurate.
Speaking to Panorama, which aired on Wednesday, ex-party officials claimed senior Labour figures had interfered in the disciplinary process of dealing with accusations of anti-Semitism.
Labour has insisted the claims were inaccurate and made by “disaffected” former staff.
In a letter to Labour General Secretary Jenny Formby, Mr Watson said the party’s response had failed those