The Glensanda Quarry in Argyll, which is the largest in Europe, is operated by the global giant Aggregate Industries which has tendered out excavation and haulage operation to Spanish-owned contractor Oban Earth Works.

As a result, GMB Scotland has warned that most of the 50 former Hargreaves employees currently employed at the quarry are expected to be let go.

The remainder of the workforce can look forward to their existing terms and conditions being ripped up with a new set of working patterns and reduced pay, GMB added.

Many of the current employees have worked at the successful quarry for over 30 years.

The union said the move may well result in litigation against the incoming Spanish company to force them to respect the TUPE Regulations.

Gary Cook, GMB Scotland organiser, said: “Despite our best efforts Oban Earth Works - the incoming contractor - are not prepared to listen.

“We have been at pains to point out that the employees are protected under the TUPE regulations which protect employees’ jobs and terms and conditions when a contract is transferred to a new employer.

“They are simply sticking two fingers up at the regulations and the hard working employees formerly of Hargreaves. This is a terrible time for GMB Scotland members working at the quarry.”

Jon Simarro, director of Oban Earth Works Ltd, told Scottish Construction Now: “We are a considerate family business and incredibly conscious of the impact job losses will have on the local community. We are highly committed to doing everything we can to reduce these as far as possible and employ as many local people as we can.

“Although details are still being finalised, it looks highly unlikely that there will be any compulsory redundancies at this stage and we are working hard to redeploy any affected employees to vacancies on Glensanda or any other opportunities within Oban or Scotland-wide.

“A full employee consultation process is now underway as supported by a Union representative as requested by GMB members.

“Oban Earth Works appreciates the impact these changes may have on the employees and local community, and commits to supporting every employee throughout the process. We are excited about the five years contract on Glensanda and realise that we can’t do that without experienced motivated staff working with us to make this contract a success.”