Five gardai who had expected to be promoted to chief superintendent have written to Tanaiste Frances Fitzgerald claiming their "unblemished careers" are being tarnished by delays in the process.
The officers are the final five from a list of 18 selected in May for promotion, but will have to go through a new series of interviews as the panel expires on December 31.
This is despite the fact eight key chief superintendent positions are vacant, including in the Dublin Metropolitan Region (DMR), which oversees requests for access to the force's Armed Response Unit.
Ms Fitzgerald is expected to take part in an event to highlight the roll-out of new garda vehicles and equipment later this week as part of the ongoing battle against gangland crime in the city.
The row over appointments comes ahead of the transfer of power for promotions from the Government to the Policing Authority.
The Tanaiste's department said the superintendents were informed by Garda Commissioner Noirin O'Sullivan that, when they applied for promotion, they would be placed on a panel that would lapse at the end of year or when the authority took over appointments.
"It is normal practice for panels to have an expiry date so as to facilitate fresh competitions," a spokesperson said.
However, the officers' letter says the declaration relating to the expiration of the panel "was presented in such a way that if the candidate didn't sign, then the interview wouldn't continue". They added that the gardai have received "advice" that the "significance of that declaration may be nullified in the way it was presented".
The letter, which has also been sent to Ms O'Sullivan and the Policing Authority, says the manner in which the five officers are being treated is "inherently unfair".
In the meantime, four of the country's chief superintendents are currently responsible for two roles due to the long list of vacancies.
Among the unfilled positions is the role of chief superintendent for the DMR, based in Harcourt Square. The chief superintendent for DMR East is currently double-jobbing in this role.
"This is the person that has a say in whether the Armed Response Unit is deployed in the city, but they are tasked with two jobs," a source said.
Similarly, the chief superintendent charged with ensuring professional standards are adhered to nationwide is also now responsible for the Garda Technical Bureau.
A garda spokesman said the appointment of chief superintendents is a matter for the Government.
"The commissioner has publicly commented on several occasions on the need for critical vacancies in the organisation to be filled," they said.