Graham Avery, who worked on the accession of other new member states, has insisted it is “obvious” that Scotland should be part of the EU family.
He told MSPs on Holyrood’s European committee that, in the event of a Yes vote in the referendum, an independent Scotland should join the EU as soon as it leaves the UK in March 2016.
Avery said: “It’s not just about fisheries but the whole system of the single market, the network of trade, economics and all those things.
“Unless Scotland continues to apply EU rules, then it becomes diabolically complicated for firms and citizens not just in the rest of the UK, but in Germany, Spain, and all round Europe.
“As is well known citizens and firms in other member states have rights in Scotland by virtue of Scotland being a member of the European Union. With Scotland no longer applying EU rules, no longer having EU obligations, they would be in a right mess.”
Mr Avery is an Honorary Director-General of the European Commission, but retired from frontline duties. Currently, he is a senior member of St. Antony’s College, Oxford University and a senior adviser at the European Policy Centre in Brussels.
He went on: “A situation where Scotland was outside the European Union and not applying European rules would be a legal nightmare for the people in the rest of the United Kingdom and the British Government has to take account of that.
“I think it would be very, very unfortunate for the rest of the United Kingdom if Scotland was not a member from day one of independence.”
Senior European figures like EU President Jose Manuel Barroso and European Council President Herman Van Rompuy, have indicated the legal position is that Scotland will be outside and have to re-apply to join after independence.
But Mr Avery today insisted that the final decision will be reached by politicians and backed the Scottish Government’s claims that Scotland would be allowed to remain inside the EU and renegotiate its membership from inside.
“It’s against the interests of other member states for Scotland not to be a member from day one of independence,” he added.