Dublin City Council has asked the Workplace Relations Commission to intervene urgently in a bid to avert two days of strike action by Dublin Fire Brigade before the end of the month.
The dispute centres on plans to change ambulance call and dispatch arrangements at Dublin Fire Brigade.
SIPTU and IMPACT have backed strike action, which would see a 24-hour stoppage on Saturday 18 March - with a second stoppage on Monday 27 March.
SIPTU Organiser Brendan O'Brien said Dublin City Council wants to relocate the Dublin Fire Brigade ambulance call and dispatch function based in the city centre to link up with the National Ambulance Service call and dispatch centre in Tallaght.
Around 45 people work in the DFB call and dispatch centre.
Mr O'Brien accepted that HIQA had raised concerns about ensuring that no calls were dropped, and that the nearest appliance would be sent promptly to an emergency.
However, he said HIQA's concerns could be addressed by streamlining the software used by the NAS centre and the DFB centres.
Meanwhile IMPACT has served notice that its 80 members in DFB will join the SIPTU stoppages amid anger over what they see as an attempt to break up the DFB Emergency Medical Service.
Dublin City Council described the DFB strike notice as disappointing and regrettable.
In a statement, it said the 2014 HIQA Review of Pre-Hospital Emergency Care Services expressed the view that current emergency ambulance control centre arrangements (primarily call-taking and ambulance dispatch) in the Dublin area are not configured to provide the best possible service to patients - adding that this represents a serious risk to patients.
The Council said that as a result, the four Dublin Local Authorities and the Health Service Executive agreed that the optimum solution, in the interest of patient safety, is that all emergency ambulance call taking and dispatch should be carried out by NAS National Emergency Operations Centre in Tallaght.
The statement says that while there have extensive consultations with the trade unions on this matter over the past two years no agreement has been reached and the City Council has not sought to implement the proposed change.
Dublin City Council said it hopes to have date for the WRC as soon as possible.
Both SIPTU and IMPACT have said they are available for talks.