Council chiefs are trying to budget for an anticipated cut of up to £57m in the 2012/13 financial year, and are forecasting a deficit of up to £170m by 2015/16.
A spokesman for the authority said yesterday that some “large-scale savings” had already been identified, such as by restructuring the spending on the city’s 25-year highways project and also by reviewing the council’s office accommodation.
However, this would bring the budget gap down to around £40m and there are still “significant savings to find” before a final budget is agreed.
Coun Bryan Lodge, deputy leader of Sheffield Council and its Cabinet member for finance, said: “We are not underestimating the size of the challenge we are facing but it is one that I am certain this council, both officers and councillors, are able to rise to.
“We are working with a two-year budget proposal so we can take a longer-term view of where funding can be spent and how it can be best targeted.
“Clearly we are focusing on the immediate year ahead as it is sharply in focus.”
Sheffield Council said that 690 posts could go in the 2012/13 financial year, from the council’s current workforce of just over 7,000.
This includes jobs that could be lost through voluntary severance, voluntary early retirement and vacancies that have not been filled.
“I would like to stress that this is an estimated figure and towards the upper end of our estimation,” Coun Lodge said.
“We are not yet in a position to confirm a definite number, as this is obviously dependent on the decisions made by councillors around the budget options.
“However this is likely to represent the worst-case scenario and we will of course do whatever we can to reduce that number.
“The council wants to hold constructive talks with the trade unions.”
Trade union Unite said yesterday that the coalition Government was to blame for the job cuts.
Unite regional officer Doug Patterson said: “These job losses could be avoided if the Government reversed its continuing and failing policies on public expenditure and adopted a U-turn in its current harsh policies to local government.
“Unite would urge councillors to leave no stone unturned in avoiding job losses and cuts to much-needed local services.”