Constitutional reformers want change as soon as possible
Downing St has played down suggestions that laws discriminating against women and Catholics in the succession to the throne are set to be changed.
Gordon Brown said at Question Time that these laws were "outdated" and the topic would be discussed with Commonwealth leaders "in due course"
But No 10 said this did not mean he would be raising the issue at this weekend's Commonwealth summit.
A spokesman said it might be discussed on the fringes of the Trinidad meeting.
Commonwealth members would be asked to approve any changes to the 1701 Act of Settlement, which bars any Catholic or anyone married to a Catholic from ascending the throne.
'Out of place'
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.
Earlier this year, it was reported Mr Brown had had preliminary discussions with Buckingham Palace over possible reforms to the laws of succession but no specific proposals have been put forward.
Mr Brown's comments during prime minister's questions were no different from views he had previously expressed, No 10 insisted, adding that the prime minister would not be using the Commonwealth meeting in Trinidad to urge change.
The Prime Minister made his remarks in the Commons when he was responding to a question by the Lib Dem MP Evan Harris.
Earlier this year, the government killed Mr Harris's private members' bill amending the 1701 Act of Settlement but promised to come forward with its own proposals.
Mr Brown said: "The Act of Succession [sic] is outdated. Most people recognise the need for change. Change can only be brought about by not only the UK but all the realms where Her Majesty is Queen.
"That is why it is important to discuss this with all members of the Commonwealth, including countries such as Australia and Canada. That is the process which will be undertaken in due course."