LONDON Prime Minister David Cameron said he backed "in principle" changes to a law on royal succession that would give any daughters born to Prince William and Kate Middleton the same right to the throne as their sons.
Cameron also said he supported a reform of an ancient rule that forbids a Catholic, or anyone married to a Catholic, from taking the throne.
"In principle I think both changes should be made," he told BBC radio on Tuesday. "But it will take time because it's not just our decision, it's a decision for others as well. We ought to have proper discussion with other countries...
"We have to recognise that the Queen is not only the queen of the United Kingdom but also of many other jurisdictions."
The issue is in focus ahead of next week's wedding of Prince William and Kate Middleton.
Under the 300-year-old law now in place, William and Kate's first-born son would eventually become king even if he had an older sister.
Male royal heirs have prior claim to the throne under the 1701 Act of Settlement.
Deputy Prime Minister Nick Clegg said on Saturday the law needed to change. Buckingham Palace declined to comment on the plans, saying it was a matter for the government.
The Queen only came to the throne because she had no brothers.
If her son Prince Charles had died before having children, the succession would have passed to Prince Andrew, bypassing the Queen's second oldest child Princess Anne.
The government's Cabinet Office has said talks have begun with Commonwealth countries that would be directly affected by any change in the rules, but added that "it would not be appropriate to release details at this stage."