In one of the adverts, which were uncovered by Construction News, a wheeled excavator driver sought for ‘up to 15 hours a day plus weekends for 10-15 weeks’. In a separate advert two 360 wheeled drivers were sought to work for ‘70-80 hours a week for a six to eight week period’.

The joint venture project which is now being built by Balfour Beatty and Galliford Try, following the collapse of Carillion earlier this year, is behind schedule and has faced “extremely serious allegations” regarding safety issues.

Unite regional co-ordinating officer, Steve Dillon, raised his concerns about the abuses on the project directly with Transport Scotland yesterday concerning what he calls the “flouting of working hours regulations” and the proper monitoring of hours worked on the project.

Mr Dillon said: “The latest revelations about the Aberdeen bypass project are disgusting, such long hours are lethal. Workers cannot work safely undertaking such long hours, this is exactly how mistakes occur and too often result in tragic accidents.

“This is the latest scandal to hit the troubled Aberdeen bypass and the Scottish government and the Health and Safety Executive simply can no longer sweep these problems under the carpet. There must be an immediate investigation into what is occurring and if necessary work should be stopped to ensure that safe, legal processes are in place.

“The rush to finish this already delayed project must not in any way be at the expense of workers’ safety or conditions.

“Balfour Beatty and Galliford Try must be held fully accountable for these adverts, it is their project and they can’t try to pass the blame onto others. To suggest they don’t know what is happening on their own site is simply not acceptable.”

Transport Scotland said it entirely refuted the claims it has placed any jobs of this description and that it is currently investigating the source of the advertisements. The transport body added that the health and safety of workers are “of the utmost importance” and that the AWPR’s Accident Frequency Rate (AFR) of 0.17 is comparable to industry standards for a project of this scale and complexity.

A Transport Scotland spokesperson told Scottish Construction Now: “The AWPR/B-T contractor has confirmed that it does not recognise the recruitment adverts mentioned within the Construction News story. No roles of this description have been placed by the contractor online or anywhere else. As soon as it became aware of the advert, the recruitment agency was contacted and requested that the advertisement be removed.

“The contractor has also confirmed that its directly employed staff and operatives work to standard terms and conditions and any overtime is undertaken on a voluntary basis.

“Transport Scotland, which met with Unite to better understand the accusations being made, would also like to add that the health and safety of those working on all major infrastructure projects and the surrounding community are of the utmost importance. As such, it will investigate all claims highlighted in relation to health and safety.”