The contractors at the Lindsey oil refinery, which saw determined strikes last month, are attempting to roll back on the agreement that brought the action to an end.
Workers were expecting to be all taken back on. But well over 100 are on paid leave.
One worker said, “We are being told that the plan for the remainder of the project is to take longer to finish it with a smaller workforce.
“This is not what we agreed to.”
The employers have responded to the plans for a national ballot of engineering construction workers by the Unite and GMB unions by reopening talks.