Around 70 labourers and scaffolders at the Glasgow Recycling and Renewable Energy Centre decided to down tools as the latest move in a pay row dating back to last June.

The Unite workers claim they are earning up to £5 an hour less than more recently hired workers, who are paid under the National Agreement for the Engineering and Construction Industry pay rates.

They say that Interserve first employed them 18 months ago was under the Construction Industry Joint Council nationally agreed pay rates, which can be £4-5 per hour below NAECI wages.

Unite say it is taking the action to strike after Interserve on Thursday rejected its calls for pay parity for the workers employed under the CIJC.

IInterserve won the contract for the plant in 2013; when completed, will handle 200,000 tonnes of Glasgow’s residual waste every year.

Around 300-400 workers are currently working on the site that is expected to be completed later this year.

Unite regional officer Stephen Deans said: “What appears to have happened is that Interserve employed the workers going on strike on the CIJC rate.

“But the firm and their subcontractors are paying new workers on the site at the higher nationally NAECI agreed rate or greater.

“They have had to employ people from across Scotland and even from outside Scotland, so they have had to pay more to attract the travelling workforce.

“What we are calling for is pay parity for all workers on the site that has a workforce of between 300 to 400 workers.

“We had a meeting with the Interserve management on Thursday and they refused to consider pay parity.

”This is very disappointing.”

An Interserve spokeswoman said: “In respect of the GRREC site in Glasgow we are disappointed that industrial action has been called, this is a multi-contractor site where employees are paid the appropriate rates for the associated trades and Interserve is aligned with this policy.”