SIPTU members employed in the National Advocacy Service (NAS) have voted overwhelmingly for strike action in a dispute over pay.
The union has accused management of failing to respect a Labour Court recommendation on staff pay.
As a government-funded body, SIPTU said the Department of Social Protection has allowed the situation to arise.
"Our members have only decided to commence a campaign of strike action because they were left with no other avenue to advance their claim for a fair pay rise," SIPTU Deputy General Secretary John King said.
"These workers provide a vital service to some of the most vulnerable people in our society."
"Our members are fully committed to their clients but believe the very future of NAS is under threat due to the failure of the organisation to provide adequate pay rises which are in line with the recommendation from the Labour Court," Mr King said.
SIPTU has warned that without adequate pay for staff, the recruitment and retention of workers in the service is in jeopardy.
The NAS said it was not in a position to comment as it has not received any formal notification of strike action.
The Department of Social Protection said that Minister Heather Humphreys is aware from the Citizens Information Board, the state body under the Department's aegis which funds the National Advocacy Service, that NAS employees have balloted for industrial action.
"The Minister understands from CIB that NAS submitted a business case to CIB in relation to pay, grades and other conditions on 10 May last, on foot of a Labour Court recommendation," a spokesperson said.
"Neither the Minister nor the Department has seen the detail of this business case as it is being considered by CIB. The Minister is also informed by CIB that it is seeking to engage with NAS and has invited them to attend a facilitated discussion this week," they added.
The Department said that Ms Humphreys encourages all parties to engage fully in this process and until it is concluded, would not be commenting further.
