A children's lobby group denies union claims the NSW foster care system is in crisis following reports vulnerable and abused children are having to sleep in motels.
The Public Service Association (PSA) has outlined desperate and risky measures caseworkers are resorting to accommodate children in a submission to the NSW upper house's inquiry.
"We're seeing more and more children being put up temporarily in motels during a crisis ... some case workers have had to put kids up in their own offices overnight or for a few nights while they look for a place," PSA assistant secretary general Steve Turner told AAP on Thursday.
According to the PSA children with nowhere to go have to be babysat in government-run community service centres during the day, and sleep in motels and holiday apartments, which in the case of one six-year-old cost the department $18,000 a fortnight.
The union says the makeshift living arrangements expose the children, many of whom have already suffered neglect and abuse, to additional risk from strangers and untrained workers.
Although "deeply concerning", the claims did not amount to a system in crisis, said Acting Deputy of the Association of Children's Welfare Agencies (ACWA), Dr Wendy Foote.
"From our in-depth understanding of the system, cases like this are an exception and, when they do happen, the reasons behind them are defensible and in the interests of the children."
Secretary of the Department of Families and Communities Services, Michael Coutts-Trotter, on Thursday told the ABC he wasn't aware of any confirmed reports of children sleeping on the office floors of their caseworkers, but said he couldn't rule it out.
He said about 350 of the 20,000 at-risk children under his department's care had spent supervised time in motels when they couldn't be placed with extended family or a carer, but it wasn't common.