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...
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