The union has raised issues over alleged non-compliance with the industry CIJC pay agreement in respect of overtime hours.

It is also unhappy about deductions made by agencies supplying labour to logistics contractor Wilson James.

Unite said the agency deductions on pay slips seen by the Enquirer could push some workers near the London Living Wage.

Unite has raised the issues with main contractor Lendlease.

A spokesperson for Lendlease said: “We’re well aware of the persistent and increasing challenge of low pay for some workers in the construction industry.  And that is why we’re proud to have achieved Living Wage Employer accreditation, which we believe helps us recruit and retain a talented workforce across all of our projects.

“Wilson James are also a Living Wage partner and they have confirmed to us that all payments made to their team members are in full compliance with the scheme. We understand that they are attempting to contact Unite in order to clarify that with them.”

Vince McCoy, Unite regional officer said: “While we recognise the London Living Wage as a base rate of pay it cannot be used to undercut the CIJC agreement. It is a base rate rather than a ceiling for rates.

“I will be meeting with Wilson James in the near future to ensure they fully understand this point.”