The PSNI has appointed a senior officer to investigate missing pensions correspondence to 300 former police officers who are concerned about their security.
First Minister Arlene Foster said the issue is of serious concern, adding: "It is vital that a full and thorough investigation takes place and all former officers and staff affected are reassured of their safety."
It comes after former police officers expressed concerns that the letters have been missing for several weeks, amid fears they may have been intercepted.
A spokesperson for the PSNI said their Pensions Branch is aware that a number of payslips collected by Royal Mail at the end of March for retired officers remain undelivered.
Royal Mail said they are aware of the matter and have told the PSNI they are trying to find the outstanding payslips amid delays caused by the coronavirus lockdown.
The PSNI spokesperson said it has "appointed a senior investigating officer who shall work with Royal Mail to establish the circumstances and address any criminal justice matters which may unfold".
"PSNI Pensions Branch do not believe that there is any information on the payslips which would identify individuals as retired officers," the spokesperson added.
DUP MLA and Policing Board member Mervyn Storey said he has spoken directly with the Chief Constable's office in relation to the concerns raised over the past 24 hours.
The PSNI spokesperson said the incident "does not currently meet the criteria for notification for the Information Commissioner's Office".
A spokesperson for the Information Commissioner's Office said people have the right to expect that organisations will handle their personal information securely and responsibly.