The Scotland Bill could be amended to give Holyrood the legal power to run an independence referendum, the Scotland Office has confirmed.
The Scottish Government has pledged to hold an independence referendum in the second half of the present Scottish Parliament, but it is thought any referendum would be merely "consultative" as Holyrood does not have power to hold a legally binding referendum.
A Scotland Office spokesman said giving Holyrood the legal power to run a referendum was one potential option of the various options under discussion.
However, he dismissed suggestions that this was now a definite option as "simply speculation".
He said: "The Scotland Bill will return to the Lords in January where these issues will be discussed in detail.
"It illustrates that the Scottish Government must end the considerable uncertainty the prospect of a referendum is causing by bringing forward its detailed plans as soon as possible."
Former Scottish Secretary Lord Forsyth said he welcomed the possibility of the referendum being legally binding.
He told BBC Radio Scotland's Good Morning Scotland programme: "I have been arguing for four years that we should have a referendum that was binding in Scotland. Who actually runs it is irrelevant.
"What matters is that we have a properly conducted campaign, that we have it properly supervised by the Electoral Commission, and that the result is binding so that if people vote for independence that is exactly what will happen, and that we end this uncertainty which is so damaging to Scotland's financial interests as soon as possible."
Lord Forsyth also called for "a proper campaign" over a period of around 12 months.
First Minister Alex Salmond said: "The Scottish Government won the right in this year's Scottish election to hold the referendum in the second half of the parliament.
"Lord Forsyth lost the right to run Scotland in 1997, when he lost every single Tory seat in Scotland.
"The Westminster parties, whose ability to meet the challenge on the constitution was questioned only yesterday by the UK Cabinet Secretary, will just have to wake up to the fact that times have changed, and that nowadays decisions on the future of Scotland will be taken in Scotland, according to the wishes of the people and the parliament."
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