The union, GMB, claims Sheffield City Council has sent official ‘redundancy notices’ to 8,500 of its staff.
The union said the notice covered changes to terms and conditions and job levels, and has blamed the Government’s policies for potentially costing jobs.
Paul Kenny, GMB general secretary speaking from the Labour Party conference in Manchester, said: ‘These official notices for 8,500 staff at Sheffield, coming on top of the notices for 26,000 in Birmingham, nail the lie that this government’s policies will not cost jobs and will lead to reduced services for the public and inferior terms and conditions for staff.
‘Service users and service providers in both Sheffield and Birmingham will fight to protect services and jobs in both major cities.
‘The blame for this reduction in services and in jobs lie firmly at the door of David Cameron and Nick Clegg.’
A spokeswoman for Sheffield City Council rebutted the claims. LocalGov.co.uk awaits a statement from the council setting out its position.