Treasury documents seen by shadow chancellor John McDonnell show that forces will have to find an extra £96 million — even after seven years of deep cuts that have slashed officer numbers by 20,000.
An extra 2,688 police officers and staff could lose their jobs if numbers have to be cut to fund the top-up payment.
Mr McDonnell said: “The Tories have tried to play a game of divide and rule over the public-sector pay cap, by first announcing a below-inflation pay offer for only prison and police officers, which in reality is just a pay cut.
“And on top of this derisory offer, Chancellor Philip Hammond is forcing departments to fund this from within their already under-pressure budgets after seven years of Tory austerity.”
Shadow policing minister Louise Haigh has already warned that forces would have to run down their general reserves if there were further cuts.
Home Office Minister Sarah Newton ludicrously claimed the additional payment would be “absolutely affordable for forces.”