A Health Information and Quality Authority inspection report has criticised the area management of Tusla in Cork for failing to record 40% of child protection and welfare allegations submitted to it against foster carers last year.
The social services watchdog says it was not fully assured that a child would not be placed with carers against whom there was an "open" allegation.
Tusla, the Child and Family Agency, is also criticised for failing to designate an authorised person to formally monitor the area's service
Tusla's Cork city and county service has the responsibility of directly overseeing children in State care living in a total of 517 foster carer households
HIQA's inspection last February judged the service seriously non-compliant with five of the eight standards reviewed.
Tusla's management records showed 17 child protection and welfare concerns or allegations in the previous year.
However, a review of the log of concerns maintained by staff turned up 29.
There were no formal systems in place to ensure the area's Foster Care Committee was notified of allegations so that it could track investigations.
And inspectors were not fully assured that a child would not be placed with carers against whom there was an "open" allegation.
Almost half (46%) of the area's foster carers had not been reviewed by Tusla for three years or more, resulting in their garda vetting not being updated.
The report says an initial review should take place one year after placement while subsequent reviews should take place at three-yearly intervals.
Nine relative carers had not been assessed or approved by the Foster Care Committee despite some children having been placed with them as far back as 2011.
37 carers who needed to be deregistered for a variety of reasons had not been formally removed from the area's panel.
The HIQA inspectors say this posed a risk that children could be placed with them.
Not all carers were subjected to garda vetting, adequate home visits or other precautions.
73 relative carers were awaiting assessment.
Two assessments took two years to complete and one took 12 months.
The report states that such delays continued to expose children to risks identified by the watchdog four years ago.
There were not enough foster carers in place to meet demand but there was no shortage of applicants waiting to be assessed as carers.
Inspectors found the service was understaffed.
HIQA says the agency's response to the finding about the assessments backlog failed to include specific timeframes for addressing it in a timely manner.
Team leaders said the volume of reviews was a challenge and was the result of insufficient resources.
Tusla has submitted an action plan to HIQA addressing the areas of its fostering service in Cork identified by the watchdog as being in need of improvement.
It says it is designed to ensure that the improvements are made in a timely way, adding that many are already under way.
In a statement, the agency says new guidelines for managing concerns and allegations of abuse or neglect against foster carers were put in place at the beginning of this month and that an audit will be conducted to ensure compliance.
It adds that garda vetting for all foster carers "has been progressed" and that a progress report on the status of current investigations will be given to the Foster Care Committee on a quarterly basis.
It also states that since April 2016, no child has been placed with a potential carer until garda vetting and other relevant checks have been completed and that all outstanding unassessed relative foster carers will be assessed by quarter one of 2018.
It reports that all assessed relative foster carers have been allocated a Fostering Link Social Worker.
All previously unallocated general foster carers now have an allocated Fostering Link Social Worker, according to the statement.
And an unspecified number of new permanent social work posts have been filled.
To ensure compliance with national policies and standards, Tusla says its management will carry out random audits on a monthly basis, and thematic audits on a quarterly basis.
An audit of foster carers' supervision will be conducted and completed in the final quarter of this year.
It says the scheduling and progressing of standard foster carer reviews over the next three years will be informed by a "foster carer review audit and planning form" which is being completed by all social workers working in the sector.
Tusla adds that HIQA's inspection report highlights good practice in the Cork area which received 1,907 referrals between January and April this year.
It highlights the finding that all children in foster care had an allocated social worker and that 92% of approved foster carers had an allocated link worker.
Welcoming the publication of HIQA's report, Patricia Finlay, Service Director, Tusla said such reports are an important measurement tool and allow Tusla to ensure that services operate at the highest possible standard.
"Foster carers open their homes and dedicate their time to children who for a range of reasons can't live with their family," she continued.
"They are the backbone of our child protection system."
The Irish Foster Care Association (IFCA) said that they were "disappointed to see so many standards were found to be non-compliant such as Garda vetting, complaints management, safe guarding and ongoing assessment and many others.
In a statement the IFCA added: "Many of the findings of the inspection reflect issues that have continually been identified in IFCA's National Support Service annual and mid-year reviews and at meetings with Tusla. IFCA has a commitment from the local Tusla area to engage in a process to further highlight and address many of the issues raised. IFCA acknowledges Tusla's undertaking that it is putting an action plan in place to address those areas of concern noted in the report."