Commonwealth secretary general Kamalesh Sharma suggested that Scotland will need to reapply for membership if it becomes independent and that the application would be referred to its existing 54 members for a decision.
SNP constitution spokesman Pete Wishart MP said Scotland would be expected to have discussions with a range of multinational organisations after independence but that its memberships will ultimately be secured.
He said: “It’s like all of the discussion about Nato and the EU, of course we would be members. We will be a new nation and we will obviously have to have conversations and discussions with all sorts of multinational organisations and institutions.
“Of course, that is what new nations will have to do and that would be expected of them. But it is nonsense in the absolute extreme to say that Scotland would not be a member of the Commonwealth. We are hosting the Commonwealth Games for goodness sake, and we are already in it as a quasi-independent member competing under our flag.”
Speaking to Newsnight Scotland, Mr Sharma said: “Speculatively, if and when, were this situation (of independence) to arise then my anticipation is that a question like this won’t have automaticity. It would be referred. The heads will have to take a view of the situation.
The correct interpretation of its membership rules would have to be examined, he said.
“It is not something that would automatically apply.”
The Scottish Government said: “In the event of a vote for independence in next year’s referendum, we look forward to Scotland taking its place as a member of the Commonwealth family of nations in its own right.”
Meanwhile, during a visit to Hawick tomorrow, First Minister Alex Salmond will repeat his prediction that Scotland will remain a member of “five unions” if it secures political independence from Westminster.
During a series of summer public meetings around Scotland, he has been promoting his belief that the Union of the Crowns, the European Union, Nato, the pound and the “social union” will persist beyond independence.
A Yes Scotland spokesman said: “Commonwealth membership is not something we have looked into. If it’s a question of whether an independent Scotland would have to reapply, whether it’s the United Nations, Europe or whatever else like the Commonwealth, it’s really for the Scottish Government to come up with the answers to that.
“We are a movement that is interested in the principle of independence. What happens after that is up to the governments that you elect.
“The White Paper that is due to be published will answer a lot of the questions that people have about independence. Equally, it is up to the No side to answer questions about what they would do, which they have so far failed to do.”
A Scotland Office spokesman said: “The legal opinion we received from professors James Crawford and Alan Boyle, which we have published, states clearly that in the event of independence, the remainder of the UK would continue as before and Scotland would form a new, separate state.
“This means the remainder of the UK would maintain its membership of international organisations on the same terms as it does now. This includes the Commonwealth, European Union, Nato, the IMF, United Nations, among many others.
“It is for the Scottish Government to explain why it has been asserting an independent Scotland would inherit membership of the EU and Nato when both organisations have made clear Scotland would have to apply to join. We now have the Commonwealth secretary general saying the same thing.”