The UN Human Rights Council said the UK must "consider holding a referendum on the desirability or otherwise of a written constitution, preferably republican".
The council has 29 members including Saudi Arabia, Cuba and Sri Lanka.
It was the Sri Lankan envoy who raised concerns over the British monarchy.
The resulting report said Britain should have a referendum on the monarchy and the need for a written constitution with a bill of rights.
The monarchy costs each adult in Britain around 62p a year but even groups representing taxpayers said there was no case for getting rid of it.
Matthew Elliott, chief executive of the TaxPayers' Alliance, said: "With so many human rights abuses around the world the UN should be busy reporting on issues of starvation, execution and the denial of the vote to huge numbers of people around the world.
"Saudi Arabia and Cuba should pay a little more attention to their own human rights record."
The UN report was also critical of the UK's treatment of immigrants from Sudan.
Syrian representaives accused the UK of discriminating against Muslims and Iran complained about the UK's record on tackling sexual discrimination.
A royal source said: "People here certainly haven't detected any appetite for a referendum. The Queen is a focus for national unity, identity and pride."
The council has 29 members including Saudi Arabia, Cuba and Sri Lanka.
It was the Sri Lankan envoy who raised concerns over the British monarchy.
The resulting report said Britain should have a referendum on the monarchy and the need for a written constitution with a bill of rights.
The monarchy costs each adult in Britain around 62p a year but even groups representing taxpayers said there was no case for getting rid of it.
Matthew Elliott, chief executive of the TaxPayers' Alliance, said: "With so many human rights abuses around the world the UN should be busy reporting on issues of starvation, execution and the denial of the vote to huge numbers of people around the world.
"Saudi Arabia and Cuba should pay a little more attention to their own human rights record."
The UN report was also critical of the UK's treatment of immigrants from Sudan.
Syrian representaives accused the UK of discriminating against Muslims and Iran complained about the UK's record on tackling sexual discrimination.
A royal source said: "People here certainly haven't detected any appetite for a referendum. The Queen is a focus for national unity, identity and pride."