The Scottish government has been granted the right to take control of the sea up to 200 miles beyond the coastline.

In one of the biggest extension of its powers since devolution, Holyrood will be allowed to take charge of marine planning, energy development and conservation at sea. The previous limit was 12 miles.

The change, which emerged as a result of the joint ministerial process between Edinburgh and London, is intended to allow Scotland and England to manage their own seas, with widespread implications for planning and conservation.

It will give the Scottish government the right to approve or turn down applications for offshore windfarms, to decide if sea-based fish farms should be allowed, or to prevent activities that threaten conservation.

Announcing the deal to MSPs in the Scottish Parliament yesterday, Richard Lochhead, the Fisheries Secretary, said: “It will support the Scottish economy by enabling us to manage marine resources coherently.

“Let's be clear - this is good news for our fishermen, our other marine industries and our precious marine environment,” he added.

The move, which was welcomed by conservation bodies and oppposition politicians, will, however, be limited by existing agreements.

Deep-sea fishing will continue to be controlled under the European Fisheries Agreement, and any decision to grant offshore wind-power developments would have to take account of defence concerns. The MoD has resisted wind-farm developments because they affect radar signals.

It was unclear whether the new powers would allow a Scottish government to influence the expansion of North Sea oil drilling. Although control of gas and oil is still a matter reserved to Westminster, there might be a clash with Holyrood if new drilling rights threatened a particularly sensitive marine environment.

Equally, if deep-sea fishing methods were destroying plant life on the North Sea bed, Scottish ministers might have powers to prevent them.

A spokesman for the SNP government admitted that there were still many details to be worked out before the transfer was effected two years from now, and potential clashes of this kind would be closely looked at.

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