Around 40 people protested against the dismissal of two street cleansing workers outside Waltham Forest town hall in east London on Thursday of last week.
The Unite, GMB and Unison unions backed the protest.
Campaigners demanded justice for the two workers employed by private company Kier and that the council take the service back in-house.
Union members say that the company dismissed two workers who had been off work sick and has acted unfairly.
A Kier manager stood close to the protesters and wrote in a notebook.
“Workers are worried that they may be victimised for attending the demonstration,” one Kier worker told Socialist Worker.
“We are protesting at the way the company treats us. We are given no respect. We don’t feel like coming into work because of it.”
Phil, a street cleansing worker employed by Verdant, came to support Kier workers. “Companies shouldn’t be able to get away with treating workers like this,” he said.
Kevin Parslow, Unite branch secretary for Waltham Forest, said, “If anybody is disciplined for attending this protest we should ballot for industrial action.”
In a statement Kier said, “Kier does not discuss any information concerning individual employees, past or present, as this is of a confidential nature.”