Dublin firefighters have served notice of two days of strike action in the dispute over ambulance services.
In a letter to city council, SIPTU says there will be a 24-hour stoppage on Saturday 18 March.
This will be followed by another on Monday 27 March.
Brendan O'Brien of SIPTU, which represent Dublin firefighters, said these will involve a full withdrawal of labour.
It follows a protest outside a Dublin City Council meeting by around 200 firefighters.
The city council wants the National Ambulance Service to take over the handling of emergency calls and has withdrawn from talks on the future of the service.
The city council believes that 999 calls should taken over by the NAS and points to a HIQA report which expressed concerns about the efficiency of having two centres covering the Dublin area.
The Dublin Fire Brigade centre in Tara St covers 90% of Dublin but the NAS centre in Tallaght covers parts of the county area.
The city council also claims that it does not get sufficient funding from the Health Service Executive for providing the fire brigade ambulance service on behalf of the four Dublin local authorities.
In the past, the HSE wanted to phase out the fire brigade ambulance service believing it could be provided for less cost.
But an expert panel reporting to an Ambulance Forum set up to investigate the issue said that removing the Tara St centre would be detrimental to the ambulance system and adversely affect patient care.
It pointed out that Tara St handled 40% of the country's emergency calls with only 7% of the €138 million budget.
And it said that more ambulances are needed.
Chair of the council's Emergency Services Committee Councillor Alison Gilliland called on council management to reengage with the Ambulance Forum.
Dublin City Council declined to comment, but assistant manager Brendan Kenny told the January meeting of the forum that there was no point in further meetings as no agreement had been reached on centralising the call and dispatch service.