The Home Secretary has again put herself at odds with police as she warned forces they will not be “let off the hook” over cuts.
Theresa May told top officers if they thought the Chancellor's unexpected move to protect police from cuts meant they could continue wasteful spending they “couldn't be more wrong”.
In a speech to chief constables and police crime commissioners, she also hit out at those who have continued to complain about budgets despite George Osborne's favourable Spending Review two weeks ago.
It is the latest in a series of uncomfortable exchanges between the police and the Home Secretary, who earlier this year accused the Police Federation of “scaremongering” and “crying wolf” over cuts.
Mrs May said while the police budget is being protected it did not mean there is a “reprieve from reform”.
She said: “The overall policing budget is protected.
“But not the wasteful and inefficient spending that we all know still exists. Because if we are to meet the challenges that lie ahead, and if we are to ensure money is well spent, then further changes will need to be made.
“It does not let you off the hook or mean you can slow the pace of change. Nor does it insulate you from the need to look for further efficiencies.
“Quite the opposite. Now – more than ever before – there is no excuse not to deliver.”
Mrs May has come under attack from rank-and-file leaders after officer numbers fell by almost 17,000.
The Home Secretary also asked chief constables and crime commissioners how specialist capabilities, such as firearms, financial crime or cyber units, could be delivered in regional teams.
The decision to protect overall police spending came amid fears cuts would leave officers unable to respond to a Paris-style attack.
The move keeps police spending in line with inflation, representing a cash rise of £900m by 2019/20.