Scottish First Minister Alex Salmond says the European Union would find a way to keep Scotland in the bloc should it vote for independence from the UK.
He also claimed on Monday that Edinburgh could assume no share of the United Kingdom's national debt if London, as planned, snubbed a formal currency union with an newly-independent Scotland.
European Commission president Jose Manuel Barroso warned on Sunday that it would be "difficult, if not impossible" for an independent Scotland to join the EU.
But in a speech to business leaders in the oil city of Aberdeen on the Scottish east coast, Salmond rebuffed that claim.
"A European Union which has admitted so many countries from all points of the European compass will find a pragmatic way to accommodate the expression of democratic will from Scotland," he said.
"The decision is one for member states, but not to recognise the democratic will of Scotland would run counter to the entire European ideal of democratic expression and inclusion.
"It would pose a challenge to the integrity of the European Union even greater and more fundamental than the threat of British withdrawal. That is why no member state has suggested that it would seek to block Scottish membership."
The September 18 referendum will ask voters: "Should Scotland be an independent country?"
An estimated 5.3 million people live in Scotland.
In a speech in Edinburgh last week, British finance minister George Osborne ruled out a formal currency union with an independent Scotland.
"If Scotland walks away from the UK, it walks away from the UK pound," he said.
The chancellor said there was "no legal reason" why the remainder of the UK would have to share the pound with Scotland.
