West Midlands Police force could lose up to 1,000 officers, a tenth of its workforce, as it makes cuts of £140 million.
Representatives of the police rank-and-file have warned up to 40,000 police officers could be axed as a result of the spending squeeze.
They said specialist units, such as those who target child abusers and wife beaters, could be hit hardest.
Chief constables have pledged to save as much cash through efficiencies and reform as possible, with the vocal encouragement of the coalition Government.
But many have warned it is impossible to protect all jobs in a sector where the wage bill can form more than 80 per cent of budgets.
Shadow Home Secretary Ed Balls said: “Job losses of this scale go beyond what both the Police Federation and KPMG have so far estimated the spending review will mean for police officer numbers. People are rightly concerned that cuts of this scale and speed will undermine the fight against crime and anti-social behaviour and take reckless risks with the safety of our communities.
Mr Balls said every police force in the country was now “having to work out the implications of the deep and immediate cuts the Home Secretary has demanded”.
“But by front-loading the cuts in the first two years, the Tory-Lib Dem Government is making it even more difficult for forces to protect the frontline by finding long-term efficiency savings,” he said.
A Home Office spokesman said: “The Home Secretary has been clear from the beginning that it is possible to maintain the visibility and availability of the police on the streets.
“We have a clear plan to cut crime, by reforming the police to make them accountable to their communities, cutting out unnecessary costs, removing the targets and paperwork that keep officers off the beat, restoring officers’ discretion over charging decisions, and giving the police the powers they need to catch and punish offenders.”