An overtime ban involving 6,000 psychiatric nurses will restart from Wednesday.
It comes after talks this evening between the Psychiatric Nurses Association and health-service management failed to reach an agreement.
Discussions have been taking place to resolve the dispute over the recruitment and retention of staff.
The union said it is disappointed at tonight's outcome but is were left with no other option given the lack of effort from management to resolve the issue.
General secretary of the PNA, Peter Hughes, said:
We suspended our position 10 days ago in relation to only working our contracted hours, we did that in good faith.
"Despite the clear understanding that the outstanding issues would be resolved, we had engagement with the employer on Wednesday, we were in the WRC all day today and we are now in a position that from Wednesday onwards, our members will only work their contracted hours."