British Prime Minister Gordon Brown will ask Kevin Rudd for Australian approval to reform the 300 year old rule that discriminates against women and members of the Royal family who marry Catholics, reports The Australian.
He will not advocate complete equality for Catholics and is expected to retain rules that hold only non-Catholics can become the head of state of Australia, Britain and 14 other countries ruled by the House of Windsor.
All 16 realms of Queen Elizabeth would have to approve any changes so Mr Brown will use the meeting in Trinidad of Commonwealth Heads of Government to raise the issue in private discussions with his colleagues, the report said.
The decade old complaints about the sexism built into the rules of succession, which mean that Anne, the Princess Royal, is outranked by her younger brothers and their children, have gained a sense of urgency because of concerns that the future heir Prince William, 27, could marry and have children in the next few years, The Australian adds.
It was the overthrow of King James II in favour of the Protestant William of Orange in 1688 that led to the ban on Catholics in that year's Bill of Rights and the 1701 Act of Settlement.
Mr Brown said the Act of Settlement was "outdated" and had "to be looked at" but that could only happen "in the context of the whole Commonwealth and all countries where the Queen is the head of state."
The ban on Catholics becoming head of state is seen as untouchable by the Church of England because of the monarch's dual role as Supreme Governor of the Church of England.
End to Catholic, female discrimination: Gordon Brown (The Australian)