Dublin City Council is being called on to make more resources available to Dublin Fire Brigade.
SIPTU says the last agreed figures on man-power are no longer enough and should be raised again.
Firefighter representatives have expressed grave concern over the withdraw from service of two appliances and the impact that this could have on the delivery of critical emergency services.
SIPTU Sector Organiser, Brendan O’Brien, said: “Our members have been extremely concerned to learn that two fire appliances have been taken out of service today.
"One appliance was based in the North Strand Fire Station and the other in Dolphin’s Barn Fire Station had just provided the first response to a recent domestic fire which was widely reported in the media.
“This ongoing depletion of fire appliance cover is due to a failure by management to maintain minimum safety critical manning levels.
"This approach runs directly counter to the SIPTU Firefighters campaign highlighting the need to maintain and expand manning levels."
"This unacceptable situation needs to be urgently addressed by providing the necessary resources to ensure Dublin Fire Brigade can maintain its safety critical emergency service."