A group of Black Labour MPs have told Keir Starmer they are "losing faith in the ability and commitment of this leadership" to tackle racism within the party.
A letter has demanded "urgent action" is taken to address a "hierarchy" of discrimination.
It has called on recommendations of a bombshell report by Martin Forde KC - which detailed the toxic culture of disputes under Jeremy Corbyn - to be put in place.
The report identified concerns that attention to cases of antisemitism and the importance they played in the "interfactional conflict" had led to the party "in effect operating a hierarchy of racism".
It found that other forms of discrimination were being ignored.
In the letter, obtained by Channel 4 News, the unnamed MPs said: "Despite our party's claims to be anti-racist ... we, our members and supporters are losing faith in the ability and commitment of this leadership to tackle the issues raised in the Forde report, and we demand urgent action."
.Mr Forde told Channel 4 News there had been "slow progress" in implementing the recommendations of his report and he was keeping a "wary eye" on the situation.
Labour insisted it is fully committed to tackling racist and discriminatory attitudes in all sections of the party.
A Labour spokesman said: "The Labour Party is fully committed to tackling racist and discriminatory attitudes wherever they arise in whatever section of the party.
"Labour has apologised for the culture and attitudes expressed by senior staff that were examined by the report.
"We have implemented the bulk of the recommendations within the report, including a number that were implemented before the report was published, and the delivery of further recommendations is under way.
"We have established one of the most robust complaints systems in the world to ensure that all complaints and disciplinary processes are dealt with fairly and impartially, and agreed and implemented codes of conduct on Islamophobia and on Afrophobia and anti-black racism which set out the minimum code of conduct expected by the party of all of its members."
The party was funding a black leadership programme and new codes of conduct were due to be agreed by the national executive committee.
Mr Forde said: "There's been slow progress. I mean, in fairness to the party, there were some changes made at the party conference before the report landed.
"Like all reports, it's about implementation. So you can make recommendations. And if they're not implemented, then, you know, the report was pointless so I'm keeping a kind of wary eye on what is and isn't done."
