Independent Scotland would be EU 'lynchpin', says Salmond

“One of the great issues facing Europe is the question of energy security. In this area Scotland is blessed. We have a key role to play in providing energy security for Europe, and in developing the low carbon technologies the world will need for the future,” Salmond will say.

"Scotland has fully 25 percent of Europe’s offshore wind and tidal potential. We have 10 percent of the EU’s wave potential. We have 60 percent of the EU’s oil reserves."

He will also point to the economic muscle of an independent Scotland, stating that "as one of the wealthiest countries, Scotland is a net financial contributor to the EU and will remain so as an independent member".

Salmond's visit to Bruges and Brussels, where he will meet with EU officials, is the latest part of a charm-offensive ahead of the referendum on 16 September when Scots will vote on whether to leave the UK.

A survey by opinion pollsters ICM last week had the anti-independence 'No' campaign marginally ahead by 42 percent to 39 percent, leaving a crucial 19 percent undecided.

Salmond's government says that if voters choose independence in the referendum it would re-write and agree the country's revised membership terms in the eighteen months after the vote before Scotland became independent in 2016.

The Scottish Nationalists believe they can secure opt-outs from the euro and the Schengen agreement on border-free travel, as well as a portion of the UK's annual rebate, currently worth around €3.5 billion per year, from the EU budget.

But the tight timetable for agreeing on new EU membership terms for Scotland is predicated on all 28 EU member countries agreeing to use Article 48 of the EU treaties which allows them to amend the treaty through an "ordinary revision procedure". This would allow Scotland to remain part of the EU without requiring a formal accession process, which could take years.

Legal opinion is divided on whether the treaty amendment procedure is possible.

But pro-Union supporters contend that the Nationalists' plans are unrealistic.

Meanwhile, in a letter sent to Salmond on Monday (28 April), foreign minister William Hague warns that the First Minister's plans are "at odds with the EU’s own rules of membership".

Negotiations on Scottish EU membership are "likely to be complex and long and the outcome would certainly prove less advantageous than the status quo", states Hague, adding that "people in Scotland deserve to have the available facts ahead of making one of the most important political decisions in the history of our union."

For his part, European Commission president Jose Manuel Barroso warned in February that it would be "extremely difficult, if not impossible, for a new member state coming out of one of our countries getting the agreement of the other [existing member states]".