Pressure is growing on the Irish police to allow a Sikh man training to be an officer to wear a turban on duty.
The man, an IT professional in his 20s training to be part of the Garda Reserve, has been told he must wear a standard issue hat.
Ciaran Cuffe, a Green Party member of Ireland's parliament, has written to Garda Commissioner Noel Conroy calling for the ban to be lifted.
"The turban is a vital part of the rules of the Sikh religion," he said.
"Sikh men are prohibited from cutting their hair or appearing in public without the turban.
"In my opinion, the wearing of a turban would in no way impinge upon the operational effectiveness of a member of the force."
An association of Sikh police officers in London has strongly criticised the decision.
The Metropolitan Police Sikh Association said An Garda Siochana's uniform policy was 40 years behind the United Kingdom.
"The question is not one of cultural integration, rather of religious rights and freedom to practise an individual's faith, regardless of jurisdiction," the group said.
The Sikh man has said he will not be taking up his post and the Irish Sikh Council has also criticised the garda position.
An Garda Siochana has insisted all members are required to wear standard issue uniform when on operational duties.