Employees of stevedore company Qube are forced to manage dangerous machinery without support, breathe carbon monoxide in confined spaces and are ''threatened by violence'' when they raise concerns about safety with their managers, sacked workers say.

The workers, their families and supporters again gathered outside Melbourne's Station Pier on Sunday morning to raise concerns about worker safety. The spokesman for the ''community assembly'' asked Fairfax Media if he could remain anonymous.

Protesters and police at Station Pier. Credit:Angela Wylie

''Workers have refused to do dangerous work and subsequently they've been sacked,'' he said. ''Their family and friends are very upset … and have been voicing their anger and frustration at the company by having a peaceful assembly here.''

The dock area around Station Pier was ''historically unsafe'', and ''a lot of heavy machinery [is] moving around … in a confined space'', he said. ''A lot of workplace practices have led to tragic injuries.''