TRADE unions have accused Sheffield Council of not revealing the full picture about redundancies at the Town Hall.
Unison claims a further 400 posts have been left empty over the last few years after people left or retired.
The union says the figure is on top of the 161 the authority said it had left unfilled in preparation for £80 million of spending cuts in 2011/12.
In total, £215 million of cuts are being made over the next three years. The council is making 270 people redundant and 300 others have volunteered to leave, making 731 job losses.
It has notified the Government that up to 800 jobs could go as a “contingency”.
But Unison regional officer Chris Jenkinson said: “What they have failed to mention is the fact that Sheffield City Council has up to a further 400 additional posts that are vacant and which will not be recruited to.
“In reality, the total number of jobs that will be axed or left vacant will be in the region of 1,200, out of a non schools workforce of just over 8,000.
“This represents around a 15 per cent cut in council jobs which will have a massive impact on the services the council will be able to deliver. What must also be remembered is that these cuts are in year one of a four-year cuts agenda.”
Mr Jenkinson said although the council said around half the 270 posts to be axed involve management and back office staff, “all workers contribute a valuable role in the delivery of services to the people of Sheffield”.
He said: “To try to placate the public by claiming that the job losses are not front line jobs is disingenuous and unacceptable. As jobs disappear other staff will be diverted to cover duties, including from front line activity.”
The trade union says staff working in departments where colleagues have left and not been replaced are under “enormous pressure” – having an impact on services they provide.
Peter Davies, of the GMB trade union, claims the council cannot count the 161 vacant posts or 300 voluntary redundancies towards the 800 reported to the Government.
He said because they have already happened and the notice refers to the 2011/12 financial year, more job losses are on the way.
Both unions are threatening strike action over cuts to terms and conditions for remaining staff.
Sheffield Council chief executive John Mothersole said: “The 161 empty posts being deleted are the number included as part of our efforts to implement the Government cuts.
“If you go back further into the past you will inevitably get higher figures for the number of empty posts. We used to employ 33,000 people many years ago. The number of jobs being lost as a result of the Government’s cuts for 2011/12 is 731.”