Drivers at the Co-op Food's West Thurrock distribution depot are threatening strike action after two disabled drivers were dismissed.
The drivers lost their jobs, with a third still facing dismissal, because they can't deliver to stores and the alternative jobs they carried out previously have been lost to outsourcing and internal reshuffling.
Unite the Union said the drivers should have been made redundant, but the Co-op had chosen to use a capability process that measured the driver's medical condition and ability resulting in them being sacked.
The Co-op said it had tried to seek alternative roles for the two colleagues but the roles had not been suitable for them.
Unite members will be balloted in the next few weeks, with action threatened in late October and the Christmas period.
Unite regional officer Paul Travers said: "The Co-op has acted in an appalling manner. The company knows the drivers are unable to deliver to stores and has been happy for them to undertake other driving roles."
The drivers deliver to more than 600 stores across London and the South East, and Unite said while the disabled drivers were capable of performing driving duties, they were unable to unload at depots.
A spokesman for the Co-op said: “We are disappointed we have not been able to resolve this through our agreed process. We have offered to speak with representatives of Unite to see if this can be resolved."
He added: "The Co-op is committed to equal opportunities and will always try and make adjustments to accommodate the different abilities of colleagues.
"Colleagues leaving our business in this way is a last resort."
