A Scottish bishop has criticised Prime Minister David Cameron for failing to act quickly to scrap the law preventing Catholics from taking the throne.
Joseph Devine, Bishop of Motherwell, said the Act of Settlement was a "scandalous" law that discriminated against members of his faith.
The act was passed by the English parliament in 1701 and extended to Scotland after the union.
It applies in countries where the Queen is head of state.
The attack follows comments from UK Constitutional Reform Minister Mark Harper that the coalition had not ruled out reform, but that any change would have to be taken "carefully and thoughtfully".
Bishop Devine said that failing to act now to repeal the law was a "sell-out" of Tory election pledges.
He added: "This law is a restriction on the private lives - and consciences - only of members of the royal family.
"But it is also the last symbol of Britain's anti-Catholic history, as the act's archaic and offensive reference to 'papists' makes clear.
"This law sets the tone for any discussion on sectarianism.
"When the monarch is free to marry a Scientologist, Muslim, Buddhist, Moonie or even a Satanist but not a Catholic, then there's something seriously wrong."
The Act of Settlement bars any Catholic or anyone married to a Catholic from ascending the throne.
The law also gives precedence to male heirs in the succession.
Opponents have long called for changes to these laws, claiming they are out of place in the 21st Century.
Bishop Devine said the prime minister was showing "alarming signs of the arrogance and disdain so often associated with power".
He continued: "What ghosts need to be buried, and feuds forgiven, before the Act of Settlement can be repealed?
"In the meantime, six million British Catholics will be unforgiving of David Cameron for breaking faith with them and denying them equality before the law."
Mr Harper faced calls from Labour in Westminster earlier this month to remove "objectionable references" to the Catholic faith from legislation.
He said: "To give you hope, we haven't ruled out change but it does need to be done carefully and thoughtfully."