An independent Scotland's re-entry to the European Union will be decided by law and not negotiation, according to a Tory MEP.

The Scottish Government insists that it will negotiate its terms of EU membership in the period between the referendum in September next year and its projected independence day in 2016.

But Conservative MEP Struan Stevenson, who is retiring next year after 15 years in the European Parliament, said the terms are already laid out in law in the Lisbon Treaty.

Some experts argue that Scotland would inherit the UK's existing EU terms as a "succession state", one that jointly succeeds the old UK member state alongside the remainder of the UK.

Mr Stevenson described this as an "invented term" at the Conservative party conference in Stirling.

"No one has ever heard of a succession state in Brussels," he said.

"As an accession state, we will go through the exact procedure laid down in the Lisbon Treaty, in law.

"Nicola Sturgeon actually told Jose Manuel Barroso, the president of the European Commission, that he was wrong when he said Scotland would be like any other new member state and would have to accede and apply for membership. She said it would be decided by politics and not by law.

"It gives a whole new meaning to the word arrogance when you hear that sort of nonsense coming from Nippy Nicky and Wee Eck. I'm sorry Nicola, it will be resolved exactly by law."

Scotland's accession would require unanimous approval from the Council of Ministers and a 75% approval in the European Parliament, he said.

"It's just possible that one or two ministers, maybe the Spanish minister, in the council won't want to give encouragement to the Catalonians or other separatist movements in Spain. I don't think it will happen but it's possible."

The EU would have to create a commissioner post for Scotland in an already-swollen European Commission, raising the prospect of a "commissioner for tartan and haggis", he said.

Scotland would be obliged to join the eurozone and set up border posts at Stranraer, Coldstream and Gretna, he insisted.

"People say this is fanciful but, I am sorry, this is law and can be tested in the European courts."

Six candidates are vying to succeed Mr Stevenson at the European Parliament elections next year, led by Ian Duncan.

Dr Duncan said: "We have a fight on our hands. Ukip has not found fertile soil here but let me say, I have spent time in Brussels watching Ukip doing nothing for the people who sent them to Brussels."

Candidate Nosheena Mobarik, a businesswoman from Glasgow who chairs CBI Scotland, said: "We need to tell people voting for Ukip is a wasted vote. It's only going to benefit Labour and Labour are not committed to renegotiating anything in Europe or in an in-out referendum."

Candidate Jamie Gardiner, a business strategy adviser, said: "In the in-out EU referendum, we will have the opportunity to reduce the number of commissioners by at least one."

Candidate Iain McGill, a businessman, said: "We need to repatriate powers from Europe. David Cameron is the only one that's going to do it. Nick Clegg doesn't follow through on his pledges and Ed Miliband is on the payroll of the unions who love stuff like working time directives. It gets in the way of business."

UK Fisheries Minister Richard Benyon said keeping the UK together and reforming the EU is necessary to secure a fair deal for Scottish fishermen.

"We are stronger together and weaker apart," he said.

"I've always believed that fishermen should always be at the heart of any discussion. They should be the architects of the new management system, working with government at every level. They should not be the helpless victims of remote and ill-informed decision making.

"We need to change the mindset now, building on this reform of how we manage our seas."