The Cairngorm ski resort near Aviemore has come under fierce fire for breaching planning permission during construction work high on one of Scotland's most-prized and protected mountain ranges.

The Cairngorm National Park Authority (CNPA) has reprimanded the ski company for creating an access track and re-engineering a slope without consent. The works were part of a scheme to replace the Shieling ski tow in Coire Cas.

The company, Natural Retreats, has been ordered to apply for retrospective planning permission for the two unauthorised developments. It has now submitted a new application, which will be considered by the park authority.

The tops of the Cairngorm mountains are one the most protected environments in Scotland. The high altitude, near-arctic conditions are home to some of the country’s rarest plants and animals.

There has long been controversy over ski developments on Cairngorm, most notably the funicular railway. The latest “destruction” caused by the replacement ski tow has angered walkers and conservationists, who complained to the authorities.

In November last year after the park authority was sent photos illustrating what was happening, it inspected the area. “The new track and bank regrading works do not have planning permission,” CNPA planning director, Murray Ferguson told the Sunday Herald.

“The CNPA informed Natural Retreats that either they should apply for planning permission for the works or reinstate those areas of ground.” All works stopped during the skiing season, and were restarted this summer.

Ferguson said that any retrospective planning applications would be called in by the CNPA for determination. “We are continuing to monitor the situation closely,” he added. “We are working closely with the company to ensure that any development and subsequent restoration works are undertaken to satisfactory standards and using best practice.”

Nick Kempe, a mountaineering campaigner who authors the parkswatchscotland blog, has highlighted the planning breaches. He warned that it was not wise to trust developers to monitor their own compliance with consents.

“While I understand because of resource issues it’s impossible for planning authorities to monitor every application, Cairngorm is not just anywhere but crucial to the wellbeing of the national park" he said. "Independent monitoring by the CNPA as planning authority should have taken place throughout the works.”

Another veteran environmental campaigner, Ron Greer, argued that the latest ski developments on Cairngorm were incompatible with the aims of the national park. They were “a thoroughly disgraceful abrogation of those principles”, he said.

“The actions behind, and outcomes of, this so-called upgrade are reprehensible enough to be considered as a monument to how not to do it. Any opprobrium and legal action taken against Natural Retreats are, and would be, thoroughly well deserved.”

Natural Retreats accepted that it had breached planning consent, but argued it was trying to improve the environment. “We’re trying to make the place better,” said the company’s Cairngorm land manager, Jim Cornfoot.

“We’re trying to make it look more natural.” He pointed out that plants only had a three-month growing season in the area, but promised that they would regenerate over two years.

The track was a sensible solution for access that would reduce damage elsewhere, he said. It would be narrowed and given a central verge, but if the CNPA so ordered, it would be removed.

According to Cornfoot, the reshaped bank was to modify previous earthworks and gave the land a more natural profile. “Although it was done without planning permission, we think it was needed,” he said. “People have got different agendas and are trying to stir up whatever they can.”