In a project update presented to the Scottish Parliament yesterday, Michael Matheson MSP said the full opening of the £745 million road improvement scheme had been delayed yet again, but could not provide a “definitive date” for completion.

The minister has now requested an “urgent” meeting with the contractors to seek clarity on the timescales for opening the remaining sections.

The 28-mile (45km) bypass was approved by Scottish ministers in 2009 and first main section, between Parkhill and Blackdog, opened in June.

Beset with delays due to weather and technical problems, the AWPR hit its largest bump in the road when Carillon collapsed at the beginning of this year.

Its full opening was finally expected this autumn but Mr Matheson told MSPs that Aberdeen Roads Ltd had pushed back the target and now hoped to complete the scheme in December.

The minister warned that a “definitive date” for its opening could not be offered because work to repair defects on the new River Don bridge were more “extensive” than initially believed and could still be affected by bad weather.

And he suggested that setting an “arbitrary date” could “compromise” that work.

Mr Matheson also revealed frustration that talks with Galliford Try to open the Craibstone to Stonehaven and Charleston section, which required a variation to the contract, have not progressed as hoped.

The minster blamed the contractor for its “simply unacceptable” failure to progress his demand to open the key 19-mile Craibstone to Stonehaven section ahead of completion of the Don crossing.

He admitted that Transport Scotland would need to find out if “lessons can be learned” about the drafting of such contracts in the future.

Mr Matheson said: “Earlier this week, I spoke with Peter Truscott, chief executive of Galliford Try, to receive an update on the progress they were making in discussing this variation with their lenders.

“Despite assurances that they were doing everything possible to open the road at the earliest opportunity, as well as a clear indication from Mr Truscott that they were making the necessary changes to the AWPR contract to open the 31.5km section, I was then disappointed to receive a letter from him which contradicted our discussion.

“It is this kind of inconsistency which is frustrating efforts to progress the opening of this new section. As recently as 12th September, Galliford Try issued a statement to markets to say the AWPR was on target to open in late Autumn 2018 and we had no reason to doubt that assessment.

“I have been urging the contractor to conclude its deliberations for some time. I repeated this to him on Monday and reiterated it again today in writing, It is now time for the contractor to stop deliberating and start acting. It now has to take the necessary steps to open the majority of this road and let the people of the North East enjoy the benefits they have been so patiently anticipating.

“I have therefore asked for unequivocal confirmation that the agreement is being progressed and when it will be concluded.”

The minister added: “After the opening of the AWPR, if there are some lessons that can be learned about how we draft some of these contracts in the future to address the type of issue that we’ve identified with the AWPR, then clear that’s a lesson that we should learn from.”