More than half of the PSNI's full-time reserve will be cut, Chief Constable Hugh Orde has decided.
The full-time reserve has faced an uncertain future
Mr Orde officially announced his decision to keep 680 reservists out of almost 1,500 at a private meeting of the Policing Board on Thursday.
A spokesman for the Superintendents' Association said it would be seeking an urgent meeting with the chief constable.
The Police Federation Central Committee has passed a motion of no confidence in the chief constable.
The federation said it questioned Mr Orde's ability to exercise independence of judgement and said it could not understand why he rejected the professional advice of it and the Superintendents' Association.
"Given the commitment and sacrifice of the full-time reserve, no officer should be required to leave the service who does not wish to go," said the federation.
"The purpose of the Patten Report was to take politics out of policing. Today, the chief constable singularly failed in observing that keystone."
Mr Orde said it was solely based on policing requirements and was one of his most challenging and difficult decisions as chief constable.
He said it was based on "an assessment of how we can deliver an effective frontline service in the environment in which we have to police".
He added: "It is an operational decision that takes the current security situation into account and I accept responsibility for it."
Mr Orde said dissident republican groups remained the "most significant threat to policing".
He added: "There is every indication that they will maintain attacks on police patrols and stations."
The vice-chairman of the Policing Board said Mr Orde had made the right decision.
Denis Bradley said the chief constable was being unfairly criticised by political leaders and the Police Federation.
Opinion has been split between nationalists and unionists over the future of the full-time reserve.
The Patten Commission recommended its disbandment, but DUP representatives told Mr Orde at a meeting on Monday that the PSNI could not afford to lose so many officers.
On Wednesday, the federation agreed a severance deal for its members in the full-time reserve.
Terry Spence, federation general secretary, said it was the best deal they could have got.
"We met with the Northern Ireland Office today - these have been very difficult negotiations which have been going on for some 18 months," he said.
He added: "It may not suit every single individual officer, in the way in which we hoped it would, but generally we believe the majority of our officers will be satisfied with what we have negotiated on their behalf.
"A significant number of officers will have an enhancement to their current pension... some officers will have a lump sum to the equivalent of £100,000."
The Patten Report planned a "peace-time" service of 7,500 regular officers and 2,500 part-timers.
The review of policing in Northern Ireland by former Hong Kong Governor Chris Patten was one of the key elements of the 1998 Good Friday Agreement.