Dafydd Elis-Thomas has been presiding officer since 1999

BBC Wales' Dragon's Eye programme understands that a government white paper about assembly powers will be published in the next few days.

Lord Elis-Thomas said it could pave the way for the assembly to shape new laws.

First Minister Rhodri Morgan said Lord Elis-Thomas had put "a particular interpretation" on the proposals.

Mr Morgan said the white paper would lead to "a new arrangement" between Westminster and Cardiff Bay.

Lord Elis-Thomas, a Plaid Cymru AM, said he understood the white paper meant the door was open for the Welsh assembly to have a legislative process which was more like primary legislation operating in Wales.

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"My understanding is there will be a way of legislating here [in the Welsh assembly] in the equivalent of primary legislation in everything but name," he said.

"The parliamentary work of making the laws will have happened here."

He said that if this development was in the white paper, it would be "a significant step forward", but said it could only happen with the consent of Parliament and a public debate.

"If this happens, that it will be a substantial development of the role of [the Welsh assembly] and it will therefore mean we have a far more effective democracy."

Lord Elis-Thomas also described the Government of Wales Act, which established the assembly in 1999, as "a constitutional mess".

"It is a great joy to me to see at last the coming of a white paper as this should always have been a parliament and organised as a parliament," she said.

Rhodri Morgan said more law-making could be done by the assembly

But Mr Morgan recommended waiting before the white paper was published before making conclusions.

"I am not sure how much of it Dafydd Elis-Thomas actually knows but whatever it is he knows, he has put a particular interpretation on it," he said.

Mr Morgan said the white paper's proposals would lead to "a new arrangement between parliament and the assembly as to how to deal with legislation".

He said this would be "a great advantage to Parliament because they have got an awful lot of parliamentary business to get through".

"Anything that lifts that burden off by being able to outsource Welsh work to the assembly is of benefit to parliament, so I would prefer to describe it as a parliamentary release mechanism," he said.

He said it could see much more law-making work being carried out in the assembly, provided it was passed by the Welsh secretary.