Downing Street has played down reports it is considering moves to end the 300-year-long ban on Roman Catholics taking the throne and eldest daughters succeeding as monarch.
A Downing Street spokesman reiterated comments made by Justice Secretary Jack Straw earlier this year stating the Government was "always ready to consider the arguments" surrounding the issue.
But the Prime Minister Gordon Brown is not believed to have been personally involved in the process and it is not Government policy.
The Guardian has reported that proposed constitutional reforms on who can succeed as monarch were included in proposals drawn up for Mr Brown by Labour MP Chris Bryant.
According to the newspaper, which has long campaigned for the changes, the Government would like to see them implemented quickly if Labour won a fourth term at the next general election.
But the Downing Street spokesman said: "To bring about changes to the law on succession would be a complex undertaking involving amendment or repeal of a number of items of related legislation, as well as requiring the consent of legislatures of member nations of the Commonwealth.
"As the Secretary of State for Justice said in the Commons on March 25, we are of course aware of the concerns felt by many and we are always ready to consider the arguments in this complex area."
Mr Bryant confirmed that he had submitted his proposals to No 10 but would not be drawn on their contents.
In a pamphlet published last week by the Local Government Association, he argued that forcing the monarch to swear to preserve the Church of England and uphold the Protestant line of succession almost certainly represented a breach of human rights.
And he suggested it was "inconceivable" that, should Prince William have a daughter before a son, she would not be the one to eventually take the throne. Sweden, he pointed out, has already changed its law to deal with such a situation.
