UK Deputy Prime Minister Nick Clegg says the British government is consulting Commonwealth countries about changing the laws on royal succession.
At present, the law of primogeniture means male heirs accede to the throne before any older sisters.
Mr Clegg, who is responsible for constitutional reform, says the issue
requires careful thought.
But he says both he and Prime Minister David Cameron are sympathetic to changing rules which seem 'a little old fashioned'.
Mr Clegg told the BBC that it was not a 'straightforward decision' because the decision would have to be approved by all Commonwealth countries.
''It's something that affects other countries - New Zealand, Canada, Australia and so on - and we're having consultation at (an) official level with those governments,'' he said.
The 1701 Act of Settlement bars any Catholic or anyone married to a Catholic from ascending to the throne, while Common Law gives precedence to male heirs in the succession of the throne.