Improvement is required in a number of children's residential centres to alleviate challenges on children, according to the Health Information and Quality Authority.
In its latest report on the inspection and monitoring of children's services last year, it found monitoring and oversight, quality assurance and risk management differed in a number of service areas.
HIQA says there are extensive demands across some service areas for children to receive initial assessments of their protection and welfare, with lengthy waiting lists in place in the areas where risk-based inspections were carried out.
There was no national approach being taken by Tusla to manage waiting lists for children and families awaiting a service from the agency, according to its Director of Regulation and Chief Inspector of Social Services, Mary Dunnion.
Ms Dunnion says: "The resulting cumulative effect of these challenges on children, their families and the children's carers, particularly the limited staffing resources in some service areas, has led to variations in the quality and timeliness of the services that children, their families and foster carers have received.
"This impacted some service areas to a greater extent, including the Tusla services that are subject to risk-based inspections, which was seen in their limited capacity to meet the demands placed on them, as well as managing existing children's cases on waiting lists".
Foster care inspections last year found that when children were allocated a social worker, they received a good quality service, and children spoke very positively about their social worker.
However, the report points out that some areas had significantly high numbers of children in care that did not have a social worker.
As a result, it says the children were not receiving a good quality service.
HIQA says there were backlogs of child-in-care reviews and a high number of care plans that were not up to date.
The quality of care plans also varied and placement plans were not routinely completed in some areas.
Risks in some children's services remain according to HIQA and while it acknowledges that Tusla continues to face a number of key challenges, it says these challenges primarily relate to the pace of implementing a workforce strategy that both involves attracting more social workers into the service and retaining current social work staff.
"There is limited capacity to meet the demands placed on social workers," according to Ms Dunnion.