Last week new assurances by the company that it was 'unlikely' there will be any compulsory redundancies at what is Europe's biggest granite quarry, were dismissed by union officials.
GMB Scotland was responding after Oban Earth Works accused the union of 'ill-advising' workers to raise grievances.
GMB Scotland had already slammed the firm for what it claimed was the blatant disregard of employee protections enshrined under TUPE regulations - rules that govern the transfer of staff between businesses - by planning to axe 25 employees, equivalent to more than half the workforce.
Oban Earth Works, a new Spanish company, was recently awarded the primary load and haul contract at Glensanda by Aggregate Industries, which operates the quarry site.
The new company is due to take over control on August 1 and last month, in an anonymous letter, members of the worried workforce said they had been informed there would be 25 job losses.
GMB Scotland has accused Oban Earth Works of 'sticking two fingers up' at employment regulations and the hard-working former Hargreaves employees.
And union leaders have now threatened litigation against the incoming Spanish company to force it to respect the TUPE regulations.
In a statement issued last Thursday on behalf of Oban Earth Works, director Jon Simarro said the company was a considerate family employer which was conscious of the impact job losses would have on the Oban community.
'We are keen to reduce these are far as possible and employ as many local people as we can. We are excited about the five-year contract on Glensanda and realise we can’t do that without experienced, motivated staff working with us to make this contract a success,' he said.
The statement went on to allege that the union had incorrect figures, claiming: 'It is likely 23 or more members of staff will remain from 38. There is a question over the number of transfering staff and we are working with Hargreaves to confirm this.
'It is unlikely that there will be any compulsory redundancies and we are working hard to re-deploy any affected employees to vacancies on Glensanda or any other opportunities near Oban and Scotland-wide.'
'The GMB has ill-advised its members on the intricacies of TUPE to the extent they have encouraged them to raise grievances which have no case in law. Hargreaves, their existing employer, has thus said it will deal with the grievances,' added Oban Earth Works.
Speaking to the Lochaber Times after reading through the statement, GMB Scotland organiser Gary Cook was dismissive of the company's latest comments over the number of redundancies.
And on the accusations of ill-advising union members, Mr Cook said: 'Why would we not encourage employees to raise grievances? It is the only way employees can challenge things.
'And claiming these changes can all be made for an ETO [economic, technology or organisational] reason under the TUPE legislation is wrong.
'Perhaps you could change the logo on overalls or the date on which people are paid but it doesn't mean you can slash the workforce in half.'
And Mr Cook confirmed that 37 union members employed at Glensanda have now lodged grievances with the company over possible redunancies and what he called the 'tearing up' of workers' terms and conditions.
'That's virtually three-quarters of the workforce which has lodged grievances and I will be writing to the company seeking union recognition for our members as a collective bargaining unit,' he said.
Highland Council leaders are also to seek clarification from the quarry operator over the jobs threat.
Council leader Margaret Davidson said that, along with Lochaber area leader Councillor Andrew Baxter, she would be seeking clarification from Aggregate Industries about what the impact will be on jobs.
'Both Councillor Baxter and I are concerned at news reports claiming that up to half of long-term jobs could be lost at the quarry and we will be seeking further information and reassurance on what TUPE arrangements will be in place. These are vitally important jobs in a fragile rural economy,' she said.
'We also wish to discuss with the GMB union what their concerns are for their members.'
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