The war of words is the latest round in the increasingly hostile dispute over plans to replace the M&E industry’s existing pay and conditions agreement.

Unite claimed that Balfour HR representatives told site meetings that the contractor planned to replace directly employed workers with agency staff.

The union also claimed that Balfour chiefs said revamped site teams would consist of one skilled worker and eight semi-skilled installers.

But a Balfour spokesman said: “Balfour Beatty Engineering Services categorically refutes the claim by Unite that it plans to cut up to 1,300 directly employed workers with semi-skilled agency labour.

“Balfour Beatty Engineering Services also categorically refutes that teams would consist of one craftsman working with eight semi-skilled installer grades.

“These are extremely irresponsible and inaccurate messages being put out by Unite.”

Unite members are currently being balloted for strike action at BBES. The ballot closes on Tuesday 29th November.