Hundreds more police officers and staff are set to be axed in the next four years as Lancashire Constabulary tries to meet government savings of £73 million.
Chief Constable Steve Finnegan said the force had already made cuts of £40 million and plans will be signed off in the next few weeks to make a further £20 million savings.
However another £13 million will have to be found and Mr Finnegan said the scale and pace of the changes were 'frightening'.
Lancashire police and crime commissioner Clive Grunshaw said the force was in danger of 'reaching a tipping point'.
Since the cuts started in 2010 around 500 police officers and 230 staff have lost their jobs including 74 PCSOs.
Mr Finnegan said a further 165 officers and 275 staff will leave the force by 2017 as part of new £20 million cut measures announced this week.
The six Lancashire divisions will be cut to three with Eastern and Pennine divisions, covering the Hyndburn and Rossendale areas, merging into one unit headed by Chief Supt Chris Bithell.
The number of chief superintendents will be reduced from ten to five and one assistant chief constable will be lost as part of measures to reduce management costs.
However police bosses have confirmed that no more police stations or front desks will close.
Mr Finnegan blasted the cuts as 'too quick and too deep'.
He said: “There is no doubt that Lancashire Constabulary is facing it's biggest challenge and the most radical changes that it has ever seen in over 30 years.
“In the next couple of weeks we will sign off further cuts of about £20 million towards that £63 million having taken out £40 million already.
“My big concern is sustainability. We will deliver the cuts we have been asked to deliver. My big concern is further cuts beyond that.
“The danger is I think going from a proactive model of policing to a reactive model of policing.
“We will begin to see some spikes around certain crime categories. At the moment we are certainly seeing some spikes around shoplifting and sexual offences.”
Mr Grunshaw said he had concerns about the government 'continually shifting the goalposts'.
He said: “These difficult cuts have come to quickly and too deeply. We have already saved £40m and this latest raft of changes will take it to just over £60m.
“It is a figure I believe takes so much away from Lancashire Police that we are in danger of reaching a tipping point.
“Every time we feel like we are making progress, that we announce the cuts and the necessary savings, the government comes back and demands more savings from us.
“I believe we need a period of consolidation and reflection about where we've come from and where we go to.”
