LONDON European Commission President Jose Manuel Barroso said on Monday a newly independent state would have to apply to join the European Union, casting doubt on assertions that an independent Scotland would automatically become a member of the bloc.
The Scottish National Party, which controls Scotland's devolved government, has pushed for Scottish independence and plans to hold a referendum on the issue in 2014.
Assurances that an independent Scotland would automatically remain a member of the EU have been a key pledge in the SNP's bid to end Scotland's 300-year-old union with England.
"If one part of a country - I am not referring now to any specific one - wants to become an independent state, of course as an independent state it has to apply to the European membership according to the rules - that is obvious," Barroso told the BBC.
Asked whether an independent country would have to renegotiate its terms, Barroso said: "Yes".
A possible major point of contention in talks between an independent Scotland and the EU could be whether Scotland has to adopt the euro currency. Scotland had planned to keep using Britain's sterling currency.
Deputy SNP leader Nicola Sturgeon believes an independent Scotland would inherit Britain's relationship with the 27-member EU. Britain is not part of the euro zone bloc, which has been convulsed by sovereign debt crises in recent months.
"We don't agree that Scotland after independence would be in a position of having to re-apply for EU membership," she said.
"There's no provision to dis-apply the EU treaties or take away European citizenship from a country or a people just because they exercise their democratic right to self-determination," she added.
Scotland already has many of the trappings of an independent nation such as its own flag, parliament, legal system, sports teams, and a distinctive national identity, but separatists believe an independent Scotland would be richer and better run.
The issue of Scottish independence is being watched closely by other European regions with separatist movements such as Catalonia and Flanders.