The police force in South Yorkshire has agreed its budget for the coming year but says cuts will "affect services".
South Yorkshire Police must save £15m next year and £40m overall by 2015.
The approved budget suggests more than 1,100 police staff will be lost over four years including 100 police officers next year.
The police authority said it had tried to create a "balanced budget" but it was "inevitable" services would be affected.
Chief Constable Medd Hughes said: "[We] have set the best that we could perhaps hope for in the circumstances.
"I know it's a worrying time for staff and the figures seem quite large, but the voluntary early severance scheme that the staff have signed up to means that we will deliver a balanced service, at least for the next year and probably the year after.
"There are risks that service options the public have come to rely on are cut out completely."
He said his "biggest fear" was losing support staff meaning frontline staff would have to complete routine administration.
The police authority, which oversees the force which currently operates with 5,600 staff, said 100 police officers and 280 support staff would be lost next year and by 2015 400 police officers and 700 police staff would have gone, with some possible redundancies.
Labour Councillor Shaun Wright, from the police authority, said: "It's going to affect all our staff. We want him [the chief constable] to retain a balanced force which provides the full range of policing services.
£2m conference bill
"There is an inevitability about it that the service will be somewhat reduced, it is an emergency service and so the public's reliance on that service will be affected."
As well as absorbing the cuts, the force will spend up to £2m on policing the Liberal Democrat conference next month in Sheffield.
Mr Wright said it was "ironic" the force would have to pay for the service for the political party who had a hand in devising the cuts.
"It could cost up to £2m and that's going to come out of South Yorkshire council tax and tax-payers money which means that we can't spend that on policing."