Garda chiefs have expressed grave concerns that a new roster system is disrupting the investigation of serious crime and terrorism.
The rosters, which were introduced in 2012, require gardai to work a six day, 10-hour rota followed by four rest days.
But several senior officers have told the Irish Independent that the system is causing a crisis for specialist and local detective units.
They say that the system as it currently operates is proving a hindrance in major investigations such as murders, shootings and drug trafficking.
"The first 24 to 48 hours after a murder are crucial to a successful conclusion but we are now regularly finding ourselves in a situation where the people who start the enquiry have to disappear for four days which loses momentum and potentially assists a killer getting away," said a source.
The rosters have resulted in squads such as the Garda National Drug Unit, the Organised Crime Unit and the National Bureau of Criminal Investigation being without adequate personnel at crucial times to make arrests or question suspects.
Gardai say that the presence of squads like the Regional Support Unit (RSU) has also been curtailed.
Management sources also fear that they will no longer have the necessary resources to intensively target gangs like the Dundon/McCarthys.
Informal talks have been taking place with unions in an attempt to "recalibrate" the so-called Westmanstown Agreement which led to the introduction of the rosters.
The rosters were rolled out in compliance with the EU Working Time Directive to ensure the health and safety of workers.
"Most other European countries sought and got a derogation from the directive on the grounds that it would have a negative impact on policing operations but Ireland did not," a source said.
A Garda spokesman confirmed that the new roster system is causing concern and this was expressed at a recent summit chaired by acting Commissioner Noirin O'Sullivan.
"Garda management is aware of the issue and are currently reviewing the new rosters which were roled out as a pilot programme two years ago, with a view to recalibrating it," the spokesman said.
"The Commissioner has appointed a senior officer who has been meeting with the representative associations to discuss the issue," he added.
Negotiations are at a "sensitive stage" and details of the discussions are being kept under wraps.
This was the first time in 40 years that the roster and working-time arrangements for gardai had been fundamentally changed.
As part of the Roster and the Working Time Agreement, personnel in the existing four unit shift structure were redeployed to fill five.
The initiative has been successful to the extent that it provides overlapping shift patterns which have seen a 25pc increase in the number of uniformed officers on the streets during periods of high demands such as the weekends.
But while it was intended to save money it has actually cost the State more because a glitch in the system has given rank-and-file officers an extra week's annual leave. On a practical level sources say that the rosters are seriously disrupting the work of detective units.
Officers who begin a murder investigation must still take their rest days despite the urgency of the case in hand.
There is a total ban on overtime which is the only way of bridging the manpower gap.
Detectives involved in questioning terror suspects or drug traffickers for up to seven days cannot stay with the interrogation process to the end.
"It is causing a crisis in our ability to investigate serious crime. It increases the risk of mistakes being made and disrupts the continuity of evidence gathering," a senior garda source said.