The oil and gas industry is better supported as part of the UK than it would be in an independent Scotland, Coalition ministers have claimed, as they pledged to help boost investment and promote exports.
Scottish Secretary Michael Moore, Business Secretary Vince Cable and Energy Secretary Ed Davey published a long-term strategy to back the industry during a visit to Aberdeen.
Speaking to an audience of oil and gas executives, they said an independent Scotland would struggle to absorb the costs of supporting the industry, which include tax breaks for exploration and scrapping old rigs.
The claims came as a consortium of oil companies led by BP announced a GBP 330 million drilling program that could lead to further development of the giant Clair field in the Atlantic, west of Shetland.
Mr. Cable said oil and gas would continue to provide 70% of Britain's energy needs into the 2040s. He said the UK Government would provide tax certainty, supply chain support and skills development as part of its long-term plan.
Dismissing the SNP s drive for independence, he said: "A bigger country is better at absorbing shocks it's simple logic. A modest change has a significant impact on GDP. In a country 10 times smaller, the shock would be proportionally bigger."
Mr. Davey said: "Only the UK can deliver what is required over a sustained period if you are going to get the most out of the oil and gas industry. The UK is a large economy that is why we can provide the support. Smaller economies have difficulty absorbing the costs."
The SNP has put oil at the heart of its case for independence. First Minister Alex Salmond insists Scotland is on the cusp of a second oil boom, though the claim was dismissed by a think-tank earlier this week.
Fergus Ewing, Scottish Energy Minister, said: " I am delighted the UK Government is following the Scottish Government s lead in recognizing the importance of the industry by launching its own oil and gas strategy.
"It highlights the positive future of the industry, the extent of reserves, and the benefit to the balance of payments and production taxes. I welcome the view there will be a long-term future for the oil and gas industry well beyond 2055."
Meanwhile the BP-led consortium including Shell, Conoco-Phillips and Chevron said drilling had already begun on the first of five wells planned over the next two years at Clair.
Up to 12 wells could be drilled, depending on initial results.
The field, holding eight billion barrels, was discovered 35 years ago but production only started in 2005 owing to the difficulty of extracting and bringing the oil ashore.
BP North Sea regional president Trevor Garlick said: "This is a major milestone and a further big commitment to the west of Shetland by BP and its co-venturers. If successful, the appraisal program could pave the way for a third phase of development at Clair. This is now a real possibility."