Leading figures in the campaigns for and against independence have clashed over the future of Scotland in the European Union.

During a debate at Edinburgh University, Better Together director Blair McDougall said it looked "increasingly unlikely" that an independent Scotland would be welcomed into the EU.

But the claim was dismissed as "absolute nonsense" by Blair Jenkins, chief executive of Yes Scotland, at an event attended by hundreds of students, university staff and school pupils.

Both were responding to comments made by European Commission president Jose Manuel Barroso, who warned at the weekend that it would be ''extremely difficult, if not impossible'' for an independent Scotland to get the necessary approval from the EU's existing member states to join.

Mr McDougall said: "For a long time the debate has been over whether we would be able to have a fast track membership process into the EU or not.

"I think that after the comments of Jose Manuel Barroso this week, that seems increasingly unlikely and it seems that we are staring in the face, at the prospect, of being not only outside our most important trading union, that of the United Kingdom - where we sell twice as much to the rest of the United Kingdom as we do to the rest of the world - but also outside, potentially for a period of time, the European Union."

But Mr Barroso's position was dismissed by Mr Jenkins as "ludicrous".

He said: "There is nothing whatsoever, no condition whatsoever, in any of the European treaties for a people and a territory that are part of the EU to excluded from the EU. It is just not possible."

Mr McDougall also challenged his counterpart to outline a plan B for the currency of an independent Scotland, after a currency union between Scotland and the rest of the UK was ruled out by UK Chancellor George Osborne and his Labour and Liberal Democrat counterparts Ed Balls and Danny Alexander last week.

He said: "Yes, the Fiscal Commission said they would prefer there to be a formal currency union. That has been ruled out. The rest of the UK get to make a decision on this and they've made a decision on this.

"The question now, and it isn't sustainable to keep ignoring it, is what would be used to replace the pound?

"Rather than pussyfooting about, just tell us; just tell us what that plan B is. People need to know."

Mr Jenkins claimed evidence showed the Chancellor's position was "not tenable" and had gone down "very, very badly" with Scots.

He said: "It's simply not possible to say that when Scotland votes Yes the rest of the UK is the continuity state, the continuity state will keep all of the assets and therefore you have no claim on the Bank of England, you have no claim on currency, so you have no claim on any of the assets - however you are up for your share of the liabilities.

"If after a Yes vote in September it should turn out that what we heard last week was not, as I rather think it was, an opening position for negotiation - let's put it no stronger than that - then if that's not the case and if that position is maintained then yes there are other options and independent Scotland could pursue.

"I think it's very important over the next period of time that the best option continues to be put forward."