Some PSNI officers have had their personal protection weapons taken from them - despite the dissident republican terror threat being officially classed as severe.
The removal of the weapons follows concerns over officers' firearms training, which in a number of cases has lapsed.
Several hundred officers could be affected, a police source told the Belfast Telegraph.
The PSNI said a decision to remove a weapon was balanced between public safety and the officer's personal safety.
But officers have voiced their concern at being left unprotected. One said the move had caused alarm.
"Police officers in Northern Ireland carry weapons for personal protection - it isn't the same as England where it's mainly for armed response or very specific emergencies," he said. "This is in the context of a severe threat level where an unarmed officer faced with an individual intent on doing them harm is effectively a sitting duck."
The development comes at a time when the terrorist threat is described as "severe".
Last month Assistant Chief Constable Stephen Martin warned it was "highly likely" that dissident republicans would try to murder members of the security forces to coincide with the Easter Rising centenary.
A PSNI officer contacted this newspaper to report that personal protection weapons were being withdrawn.
He said there was serious concern among those who had been left without protection.
"The firearms are being removed with no immediate training for the officers in question," he told the Belfast Telegraph. "The officers aren't being trained through no fault of their own.
"Some of them might have restrictions, for example, on their duties - injuries and so on - and therefore aren't able to attend firearms training.
"What it comes down to is a balance for police management about where they see the risk factor as being greatest. Someone hurting themselves because they haven't been trained, and therefore suing the Police Service, or someone going out this evening, being attacked and not being able to defend themselves.
"They see the former as being the higher risk factor, because obviously it's a corporate risk."
The officer said he believed several hundred of his colleagues could be affected.
He said they were told within the last week that their weapons were being removed. "There is a lot of concern," he added.
"Because they carry these as personal protection weapons, they're removing that protection from them because these weapons are carried on and off duty."
Mark Lindsay, who chairs the Police Federation for Northern Ireland, said the organisation had been working with PSNI command to resolve the matter.
He acknowledged it was essential for officers to complete refresher training, but said physical injury and long-term psychological illnesses had caused problems.
"In our view, the service could have shown greater understanding to the dilemma officers faced and allowed more time to reduce the backlog," Mr Lindsay said.
"Inflexible work patterns, last-minute rostering, operational demands and sick leave have all contributed to the problem. This is not solely the fault of individual officers who are working to plug gaps in the service.
"We made representations to management and extra training sessions have been provided for firearms refreshers.
"We remain overstretched and understrength and it's inevitable that cracks will appear.
"This is a symptom of a service that must show flexibility and common sense whenever officers are giving their all to the job.
"The removal of a firearm should not be the first response, but should take into consideration a number of factors, including that individual's role and the current threat."
Deputy Chief Constable Drew Harris confirmed the PSNI was aware of officers whose training had lapsed.
He said any decision to remove a weapon was taken after careful consideration.
"PSNI has audited police officer attendance at service pistol refresher training and as a result a number of officers were identified whose training had lapsed," he told the Belfast Telegraph.
"Officers are obliged to maintain their competence and to continue to demonstrate proficiency and safety in use of the service pistol through refresher training. Where an officer's training has lapsed, their continued retention of a service pistol is considered by a senior officer.
"A decision to remove a service pistol is a balance between public safety, public confidence in the Police Service and the officer's personal safety."
In March prison officer Adrian Ismay died as a result of a dissident bomb attack on his van in east Belfast.
Speaking after the attack, ACC Martin warned of a heightened threat from dissidents.
"There is a severe threat, an attack is highly likely," he said. "We believe that the primary focus of those attacks are police officers, prison officers and soldiers."