The building plans have not yet been costed

The building, earmarked for Inverness, was unveiled by representatives from SNH and site developer Robertson Group.

The decision to move the quango from Edinburgh to the Highlands became embroiled in controversy after staff said they had not been consulted.

The office in the Westercraigs area is intended to be an environment friendly public sector development.

The plans have achieved an "excellent" rating based on the building research establishment environmental assessment method (BREEAM).

BREEAM is regarded as the UK construction industry's benchmark of best practice for the environment.

John Markland, SNH Chairman, said: "We intend our HQ to be an important statement about our commitment to sustainable development.

NEW QUANGO BUILDING Artists produce impressions of the environmentally-friendly Inverness building In pictures

"I think what we are looking at is a building which will serve the needs of SNH and the environment very well indeed.

"We hope others will follow its example - and there is no reason they should not. This is a practical, working building which also embodies the best in environmental practice."

Artists' illustrations of the building show a naturally-ventilated design with an airy central atrium and office space for up to 300 workers.

An aerial view of the HQ shows three adjoining buildings surrounded by woodland, timber deck and Caithness flagstone paving, with the main office area as the centre-piece of the plans.

Inside, staff will be situated on three floors, with beams propping up a sloping glass roof.

The Scottish Natural Heritage relocation proved controversial

As no contract has been signed, it is not yet possible to give an indication of the cost of the project.

The building will be built on the site of the Craig Dunain nurses' home, subject to a development agreement being signed.

Scottish Natural Heritage is the Scottish Executive's statutory adviser on the conservation, understanding and sustainable use of the natural heritage.

Plans to relocate its staff from Edinburgh to Inverness were first unveiled in March last year.

It remains unclear how many staff will eventually take up jobs in Inverness.

A staff survey is due to be conducted by SNH within the next month to determine the intentions of staff.

The building project remains on schedule to be handed over to SNH on March 1, 2006, with a view to staff moving in from 31 March.