Police have been told to prepare for job losses as senior officers try to find £35 million of cuts.
Sussex chief constable Martin Richards has told officers and staff falling Government funding means the force could be cut over the next five years.
The announcement provoked fears there will be fewer police on the streets and an expected recession-linked rise in crime could go unchecked.
The news followed similar announcements from local authorities across the county of possible redundancies.
Mr Richards has issued a memo to all officers and staff warning the force’s financial forecast showed £5 million must be saved in 2010/2011, and £7.5 million every year after that until 2015.
The key lines in the message read: "At this stage, nothing is ruled in or ruled out. We are considering all options as to how we deliver policing and our priorities within the funding available.
"Although the force will look at non-pay budgets, it is unlikely that the future funding shortfalls will be absorbed without some impact upon the size of the workforce over the next few years."
The force is already operating with about 300 fewer offices than the 3,500 figure Sussex Police Federation estimates is needed.
Police officers cannot be made redundant by law so any cuts to their number would have to be through departing officers not being replaced.
But the 2,400 staff employed by the force would not be immune from redundancy, including 300 police community support officers.
Sussex Police Authority, which funds the force, has only just completed a round of £10 million of savings demanded by the Government.
Brian Stockham, the chairman of Sussex Police Federation, which represents junior officers in the county, said: “We would be very, very sceptical of any scheme that reduces police officer numbers.
“At the end of the day policing is a very complex, highly technological activity these days but the one thing you can't do without are warranted officers to catch criminals and deal with
Unison, the union representing police staff, said it was aware of the situation but refused to comment.
Green Brighton and Hove city councillor Ben Duncan, who also sits on Sussex Police Authority, said: "Make no mistake, this will mean
fewer public services, greater public sector unemployment and fewer coppers on our streets.”
In the last financial year the authority spent £180 million on employee pay and £44 million on pensions contributions, ending the period with 3,186 officers and 2,481 staff in April.
This year it is operating on a budget of £252.8 million after receiving £169.8 million of central Government funding and another £83.5 million from the council tax precept, as well as grants for
specific areas of work.
It faces losing more than £2 million of funds it had invested in banks which collapsed in Iceland.
Michael Barrow, a senior lecturer in economics at the University of Sussex, said the cuts were likely to set the tone for coming years as the
country copes with the recession.
He said: “A lot of expenditure is on personnel and therefore if you really want to make a big cut you have to stop employing people.”