Report found problems in Dublin North-West
The President of the Irish Association of Social Workers says the sector needs a massive boost in funding.
It comes after a report found inspectors in Dublin North-West were not assured that all children in foster care were safe.
The Health Information and Quality Authority (HIQA) report also found that vulnerable children in State care are being cared for by foster parents who were previously found to be unsuitable for the task.
Furthermore, some children remained in placements even though allegations had been raised about their foster carers.
The report says that in 2009, 2010 and 2011 "serious deficits" were found on inspections.
It says that sibling groups were not always placed together, and children did not have easy access to aftercare service.
It adds that although children were aware of their rights, they were not always supported in exercising them and that a robust complaints procedure for the children was not in place.
It found that 41% of children in foster care were placed in foster homes outside of the local health area, which made maintaining contact with family members more difficult.
It also says that 65% of foster carers had a link social worker to support them, but 35% did not.
The Minister for Children Frances Fitzgerald has described the report as unacceptable.
President of the Irish Association of Social Workers is Ineke Durville.
She told Breakfast here on Newstalk that compared to other jurisdictions, Ireland is under-staffed and under-funded.