THE cost of building a controversial 28-mile bypass around Aberdeen could exceed previous estimates of £400 million, its backers have admitted, after a legal challenge to the route was swept aside.

The ruling by the Court of Session to throw out objections by campaign group Road Sense and a local organic farmer gave ministers the go-ahead to proceed with the Aberdeen Western Peripheral Route (AWPR), more than eight years after it was first given Government backing.

But the project, which was originally due to be completed by this year, will be subjected to a review to determine accurate costs and timescales, with sources admitting a previous budget of between £295m and £395m, produced in 2005, is out of date.

Transport Minister Keith Brown declined to give a timescale for the project but welcomed yesterday’s decision by the Court of Session. He said: “The Scottish Government remains totally committed to the AWPR being completed as soon as possible and we are pleased we can now move forward with this project which is vital to the future prosperity of the north-east and Scotland as a whole.”

Yesterday’s ruling was welcomed by businesses and politicians in the north- east, who have argued the AWPR, comprising the ring road and “fast link” road connecting it to Stonehaven to the south, is essential to improve traffic flows in Scotland’s most congested city.

But it has faced a series of challenges by environmental groups and residents who have objected to its impact on communities and argue it would encourage greater car use.

The scheme was redrawn in 2005 after objections by residents about an earlier route and was given final approval by Finance Minister John Swinney in December 2009, following a public local inquiry a year earlier.

But it faced further delays after campaign group Road Sense launched legal action earlier this year, claiming it did not have a chance to object during the inquiry, along with John Fraser, who argued his organic farm near Stonehaven would be threatened by the project. Both claims were rejected by Lord Tyre yesterday.

Transport Scotland confirmed it would fund the AWPR as previously indicated through its non-profit distributing model, a form of public-private partnership which caps private-sector profits. Critics have said the model is untested, having never been used for a major infrastructure project.

There have also been questions over how Aberdeen and Aberdeenshire councils, who are expected to provide 19% funding between them, will find the money amid a financial squeeze. Both councils re-affirmed their commitment to the project yesterday.

An Aberdeenshire Council spokesman said: “Clearly, before we are able to progress this we will have to review the timescales, project plan and project costings.”

Lewis Macdonald, Labour’s transport spokesman, welcomed yesterday’s ruling and called on the Scottish Government to begin work on the project “immediately”.

“Delivery of the AWPR is crucial to the economic success of the north-east and, under the plans of the previous Labour-led Scottish Government, this road should have been opened this year. Instead, we have faced delay after delay. The SNP can no longer justify delaying the project any further,” he said.

Stan Blackley, chief executive of Friends of the Earth Scotland, said: “The Scottish Government seems addicted to Tarmac yet has set itself demanding targets with regard to tackling climate change. This goes to show that Scottish Ministers just aren’t able to see the bigger picture.

“You cannot cut carbon emissions and tackle climate change while simultaneously building massive new roads.”