Refuse workers in Brighton say bosses are attempting to “intimidate” them.
Cityclean staff at Brighton and Hove City Council have been taking unofficial industrial action for the last month.
They are protesting against planned changes to overtime and allowance payments.
With workers sticking to their contractual obligations, crews have been refusing to pick up waste outside containers and ending their rounds on time.
Managers visited the Hollingdean depot and warned workers they could face disciplinary proceedings.
GMB union reps called it “intimidation and threatening behaviour”.