Mechanical, electrical and logistics workers are understood to have downed tools at Hinkley Point C in reaction to plans to cut travel allowances.
The Enquirer understands that a number of the workforce refused to come in yesterday as the dispute erupted into unofficial action.
A site source said: “Hundreds of workers for Balfour Beatty and NGBailey did not turn up for work today after rejecting a 50% cut to their travel allowances. “
Unite and GMB unions are now planning to ballot for industrial action over the cuts.
Client Hinkley Point C would not comment on the dispute.