The former first minister, Henry McLeish, has said it is time for a debate and review of the powers of the Scottish Parliament.
Mr McLeish says more powers could be negotiated
His comments follow hints from Jack McConnell, the current first minister, that he may be in favour of reform.
Mr McLeish said an all-party commission could examine whether specific areas should remain with Westminster, such as immigration and gun law.
But many Labour MSPs oppose more powers being devolved to Scotland.
Speaking on Radio Scotland's Five Live, Mr McLeish said after six years of the Scottish parliament, there was now a case for looking closely at some of the issues around.
He said: "Why can't we devise a system whereby we can use a reverse of the Sewel motion and actually legislate for some parts of reserved powers at Westminster in Scotland?"
"We have an ageing population and a declining workforce issue, and therefore might need to act differently.
"Another example is guns. Why on earth should we sell guns in Scotland, if the first minister, the Scottish people, the executive and parliament feel they should be going further?"
A senior figure involved in the setting up of the Scottish Parliament, Canon Kenyon Wright, said Scotland should take control of any possible changes in the relationship between Holyrood and Westminster.
"If there are going to be further changes, and I think the time has come when there should be, these should be fought here in Scotland," he said.
He said there should be a permanent constitutional commission to consider proposed changes to Holyrood powers or procedures, so that they could not be imposed on Scotland by Westminster.
Canon Kenyon Wright suggested fiscal autonomy might be an area where an extension of power would be valid.
However, Labour MP Ian Davidson said: "Until they've actually managed to deal adequately with the social problems that Scotland faces, with which they are already equipped with the powers, then it seems to me they ought not to be asking for additional powers."
Mr McLeish said opposition from Westminster, meant Holyrood should negotiate power on the basis of individual issues such as immigration or airguns.
"We've got to argue with Westminster on the basis of facts and figures and not on ideology - on the idea that we want more powers per se."
He added that he did not favour changes to tax raising powers, but said an all-party group should be set up to examine all the issues.