Keir Starmer has been urged to close a legal loophole meaning the Royal Family isn't subject to equality laws which other employers must follow.
Campaigners within the Labour Party say there is "no justification" for the monarchy being exempt from the Equality Act - and say a Labour government must act.
A motion put forward to party chiefs demands legal protection against discrimination is awarded to those who work for the royals.
Currently these workers aren't able to complain to the courts if they think they've been discriminated against because of their race, gender, sexuality or disability.
Ben Clinton, co-ordinator for fringe group Labour for a Republic, told The Mirror: "The concept of the Royal Family exempting themselves from the Equality Act, it contradicts what the Labour Party stands for.
"We believe it's morally wrong."
He said the group hopes to see the call included within a Labour manifesto, stating: "People rightly expect the head of state to set an example."
The group's motion, put before the party's National Policy Forum (NPF), states: "No employer should be free to discriminate on the grounds of race, sexuality, gender or disability, regardless of who that employer is.
Labour must take action to ensure that the royal family is subject to the Equality Act and provide these workers with the protection they deserve."
Mr Clinton said he is "optimistic" that the group's motion will be adopted by a Constituency Labour Group (CLG), who will put it forward to be considered by Labour chiefs.
"When we talk to people within the party, they're surprised this should be the case for the Royal Family," he said.
In 2021 an investigation by The Guardian found that the late Queen was personally exempted from more than 160 laws, including the Equality Act.
These exemptions were expected to be passed down to her son when he ascended to the throne.
Buckingham Palace said at the time that it had a "separate process" for dealing with allegations of discrimination made by workers, but did not say what this involved.
A government explanation note alongside the 2010 Act states: "The section does not affect the Sovereign in her private capacity."
Buckingham Palace declined to comment when contacted by The Mirror.
