THE Electoral Commission has demanded a statutory role in the framing of the question to be put to voters in the independence referendum.

But it says it would not be appropriate to comment on any proposed question before it had concluded a formal assessment and reported to Parliament, and it has not taken a view on whether the ballot should include a question on extended powers in addition to the independence question.

It also indicated a referendum could be scheduled for next year rather Alex Salmond's preferred option of autumn 2014.

The independent watchdog says it has "no pre-determined view in the merits of asking one question at a referendum or more than one question".

John McCormick, Electoral Commissioner for Scotland, said: "A clear process for agreeing the question that includes sufficient time for it to be independently tested with voters will be particularly important."

In its submission to the separate consultations being run by the UK and Scottish Governments, the Commission says: "It is essential that voters can easily understand the question and its implications. While the decision on the final referendum question wording is for parliamentarians to take, their scrutiny of the question should be informed by clear and independent advice on the proposed question based on independent and transparent research with voters."

On extending the vote to 16 and 17-year-olds, it says there are "practical challenges" to ensuring they had a fair and equal opportunity to participate.

A Scottish Government spokeswoman said: "The Scottish Government and the Electoral Commission are agreed on the fact that the question should be properly and independently tested. We are happy to work with the Commission to put the role that the Commission will play in that on an appropriate statutory basis."

A Scottish Office spokesman said the submission should give the Scottish Government "food for thought" and it confirmed that September next year was "completely achievable" regarding the timetable set out by Scottish Secretary Michael Moore.

Meanwhile, David Cameron's former tutor said yesterday the Government was wrong to try to exclude the "devo max" question from the independence referendum.

Professor Vernon Bogdanor, from King's College London, also criticised the Prime Minister's recent offer of undefined extra powers if Scotland rejects independence, comparing it to a "mystery prize".

But in a blow to Mr Salmond, Prof Bogdanor, one of the UK's most respected constitutional experts, called for the vote to be held before 2014, warning of the economic damage caused by a similar referendum in Quebec.

Prof Bogdanor, who taught Mr Cameron at Oxford, was part of a group of leading academics who told MPs that devo max had to be included.

Putting the third option on the ballot paper reflected what the public, if not all political parties, wanted, said the group, which also included constitutional expert Professor Iain McLean from Oxford, Professor John Curtice, from the University of Strathclyde, and Peter Kellner, president of YouGov.

However, they agreed devo max had to be defined more clearly before it could be offered to voters. And they told members of the House of Commons Scottish Affairs Committee that the Scottish Government's preferred question for the referendum was "leading".