Trade union Unite said there is a dispute over the level of bonus payments under the NAECI (National Agreement for the Engineering Construction Industry) agreement which covers the workers.

The ballot opens today and closes on 28 November.

Around 200 Unite members are employed on construction engineering maintenance contracts. The workforce are split between Altrad, Bilfinger, and Kaefer.

The contractors are seeking to secure the maximum bonus of £2.37 an hour under the terms of the NAECI agreement to offset rampant inflation rate which now stands at 12.6% (RPI).

Unite general secretary Sharon Graham said: “Energy companies like ExxonMobil are making record profits of hundreds of billions, yet there is apparently no money available for hard pressed workers, who are essential to the Mossmorran plant operations.

“Unite’s members are determined to fight for what they deserve especially when and they we see major corporations fanning the flames of rampant profiteering. Our workers will be receiving Unite’s unflinching support.”

Due to the nature of the work undertaken by the construction workers any industrial action will result in disruption and delays to the operations at Mossmorran.

Bob MacGregor, Unite industrial officer, added: “Unite’s members working for Altrad, Bilfinger, and Kaefer at the Mossmorran plant are angry at being denied what they are owed and deserve under the terms of the NAECI agreement. Any strike action will be entirely of the employers’ own making due to their penny-pinching. They have had every chance to resolve this dispute through negotiation but have chosen not to do so.”