The Government is facing court action by England and Wales police chiefs over plans to impose more cuts to the service.
They have told ministers that plans to make forces fund a £420m pension deficit is a cut too far and they will challenge it in the High Court, according to The Guardian.
Forces have already been subject to overall budget cuts of almost 20 per cent since 2010 and the latest plans could see the jobs of up to 10,000 more frontline officers go.
The National Police Chiefs Council (NPCC) has now written to the Treasury saying it will seek a judicial review unless it scraps the decision.
It came after Treasury officials re-calculated how much each of the 43 England and Wales forces should be paying into the police pension scheme.
The result was an extra bill of £420m which forces were told they would have to fund themselves.
But the NPCC, which represents chief constables and other senior officers, has rejected the demand and instructed a barrister to start proceedings.
It says the £420m bill could mean 10,000 fewer officers on patrol if it is funded entirely by cutbacks.
Senior officers at the three largest forces in England and Wales warned last week that new cuts would leave them with the lowest number of officers since the 1970s.
The National Audit Office and the Commons’ home affairs select committee have also warned that cuts had left forces in danger of becoming “irrelevant.”
Chancellor Philip Hammond awarded police an extra £160m for counter-terrorism activities in this week’s Budget, but there was no new cash for local forces.
West Midlands chief constable Dave Thompson said last week: “We are struggling to deliver a service to the public.
“I think criminals are well aware now how stretched we are. These further cuts will leave us smaller than we have ever been.”
Merseyside chief constable Andy Cooke, said: “The impact of the proposed changes on police officer pensions cannot, and should not, be underestimated.
“It is incumbent upon me to ensure that those who will make the final decisions in relation to the pension changes understand the crippling impact these changes will have.”
Home Secretary Sajid Javid told police chiefs in the summer that he supports their calls for more funding.
He reiterated this at a joint summit of the NPCC and the Association of Police and Crime Commissioners in Westminster today.
Mr Javid said he and Chancellor Philip Hammond will ensure police have “the resources they need” when the police budget settlement for 2019-20 is announced in December.