Fashion designer Stella McCartney's plan to build a £5 million modernist home in the Scottish Highlands is facing further delays over otters.

A leading otter charity has warned that construction must be 'stopped immediately' if cubs are found.

The charity also said someone must monitor the holts on the land constantly while building work takes place. 

The location, known as Commando Rock, was once a place where elite troops were trained for critical missions during the Second World War.

However the daughter of Beatles legend Sir Paul, has become embroiled in her own war at Commando Rock after dozens of objectors accused the famously pro-green activist of hypocrisy in her approach to the build, which some have labelled an act of environmental vandalism.

More than 60 letters of objection warned it could threaten local wildlife including otters and pine martens.

Now a long-awaited otter survey has been lodged which could potentially clear a major hurdle in Ms McCartney and her husband Alasdhair Willis application to Highland Council for planning permission.

The couple previously hired conservationists in an attempt to prove no otters were living in the surrounding area, however evidence mounted that the mammals were living in the area, leading to the specialist survey which was compiled in November.

Ms McCartney and husband Alasdhair Willis, 55, the chief creative officer with global shoe brand Adidas

The couple are seeking permission to build a sustainable, low-profile house on the Moidart Peninsula.

Ecologist Dr Leon Durbin had previously taken to a canoe to prove otters are threatened by the development, which he has objected to.

Now in a new submission Grace Yoxon of the world-leading Skye-based International Otter Survival Fund, says if it had not been for Dr Durbin the application 'may have been successful which she said could have been 'disastrous' for the resident otters.

She said: 'At that time the otter survey was totally inadequate and had completely failed to identify and record any otter activity e.g. Holts, runs, tracks, etc. How they failed to find this evidence certainly does question their competence in otter surveying,' she wrote.

'It is good to see that a second survey has now been done which does record the abundance of activity at this site.

'It is worrying though that if Dr Leon Durbin had not confirmed this evidence with video proof then the application may have been successful with potentially disastrous consequences for the resident otters there.

'Dr Durbin has given a very full and detailed comment on the application as it stands. I therefore do not need to go into all the aspects he mentions and I would like it noted that I support his comments.'