New environmental designations for the seas around Orkney would be "catastrophic" for the islands, sterilising the main harbour area and preventing vital green energy development, ministers are being warned.

Orkney Islands Council (OIC) sees this as the biggest threat it is currently facing and is now calling on the Scottish Government to put proposals for the new marine Special Protection Areas (SPAs) on "immediate hold" rather than go out to consultation.

Two draft SPAs are proposed for Orkney. The first covers the world famous natural harbour of Scapa Flow, home to the Flotta oil terminal, as well as the Pentland Firth. The second would encompass a large area to the north of the Orkney Mainland.

SPAs are designated under European legislation for the protection of rare, vulnerable and migratory birds. The council say the proposals are unnecessary and prioritise conservation objectives ahead of new, or in some cases existing, human activity.

In a letter to Richard Lochhead, Cabinet Secretary for Rural Affairs, Food and the Environment, the council sets out its opposition.

OIC Convener Steven Heddle said: "We see this as the biggest threat currently facing the council and our local community.

"The proposed conservation designations cover a massive area and, if imposed upon us, could effectively sterilise Scapa Flow, our prime harbour area, from future development. This is also the case for the Pentland Firth and Westray Firth, areas widely recognised as Scotland's great resources for tidal energy."

He said putting the two draft SPAs out to consultation set in train a process that could result in their designation. "Their restrictions come into immediate effect as soon as the consultation commences and before there has been a chance for full and proper scrutiny of the scientific case."

He said these "unnecessarily draconian designations" could thwart the aspirations of the council and the Scottish Government to see marine renewable energy production, flourish in island waters.

"That would be catastrophic for Orkney and Scotland as a whole."

He added: "The projection of wildlife and our local environment is of great importance to us. Scapa Flow, under the stewardship of the council, has served as a major oil port for four decades and has a marine environment widely regarded as pristine."

He said Orkney took its environmental responsibilities very seriously, but saw the proposed SPAs as an unnecessary step too far which would have a "devastating impact on Orkney." They would be uniquely detrimental to Orkney compared to other coastal areas in Scotland.

"We understand that these matters rely on scientific evidence. But at this stage we have yet to see up to date scientific evidence that these proposed designations are necessary or will be effective in delivering the conservation objectives which the government intends."

A spokesman for the Scottish Government said ministers were considering the introduction of 14 draft SPAs and four Marine Protected Areas following consultation this summer.

"Sites are designated on scientific basis and the identification of these additional draft SPAs sites has involved years of research by the Joint Nature Conservation Committee and assessment against the UK SPA Selection Guidelines. These include two in Orkney waters to help protect seabirds, with evidence that a very high proportion of activity is within the Scapa Flow harbour area.

"We recognise these areas are important for development and investment in Orkney waters, and also recognise Orkney's strong track record of managing licensed activities in areas with designations. The aim of the SPAs is not to prevent development, and with suitable mitigation, assessment and monitoring the Scottish Government is confident that development can continue in Orkney waters alongside an SPA.

Mr Lochhead would respond to Mr Heddle in due course.