Councils are struggling with a “last-minute” dash to find homes for children coming into care due to rising demand and a shortage of suitable placements, Ofsted has warned.

The regulator said there were particular difficulties in finding placements for children with more complex needs and older children.

It said private providers of children’s homes have more power to choose which children they take, placements are costly, and there are capacity issues within the social care workforce and a shortage of foster carers.

In a report about local authorities’ planning for sufficiency, Ofsted said difficulty forecasting demand and the need to find placements rapidly mean councils often struggle to plan, and have to respond to cases “as and when they arise”.

Councils are also caring for more unaccompanied asylum-seeking children, but do not always know how many children they will become responsible for in advance, which hinders planning.

But even when local authorities can plan, it said there is often a lack of available accommodation and care for children with more complex needs.

It heard from some council representatives who said it has “never been harder” to find suitable homes.

Social workers said they are spending lots of time chasing individual placements, which takes them away from direct work with families.

Delays in finding suitable placements for children can compound the impact of trauma, while Ofsted said there is also a shared concern about the mental health of staff “who are having to make matches they know are not right and are likely to break down”.

Ofsted also noted that some councils reported tension in their relationships with private providers, saying that they “cherry-picked” children they accept into their care.

One senior commissioning officer said: “Providers are holding and waiting for those slightly easier children.

“The providers have the market and choice… We are all on the phone to the same providers and begging them to the point where they can charge us anything.”

Ofsted said it had also heard that some providers are reluctant to take children with complex needs for fear of being downgraded at inspection.

It warned that “too often” councils are forced to place children in unregistered provision because of a lack of suitable, regulated alternatives.

The regulator also said some councils expressed concern over an ageing foster carer population in their area, with one London council saying it is ‘sleepwalking into a problem’ because half of its foster carers are set to retire in the next decade.

Around 40% of foster carers in England are aged 50 or over, which could affect continuity of care as older foster carers tend to look for matches with younger children, Ofsted said.

But it said its data shows most new foster carers are in their 30s and 40s, which suggests an ageing foster carer population may not be occurring nationally.

While many councils are trying to recruit more foster carers, some believe the rising cost of living is deterring prospective fosterers as allowances have not risen at a comparable rate.

One fostering service manager said: “I’m sure there are loads of people out there who would make fantastic foster carers but actually, with the kind of young people and the trauma they have experienced and the needs they’ve got, you probably do need someone around 24/7 and many people now cannot afford to be around 24/7.”

Yvette Stanley, Ofsted’s national director for regulation and social care, said: “More children are coming into care, many with high-level physical and mental health needs.

“The need to find places for these children quickly overrides local authorities’ long-term planning.

“It is clear that these findings are set against the issues affecting children’s social care nationally, and local authorities cannot solve the sufficiency issue on their own.

“There is a lack of suitable homes in the right places, particularly for children with the most complex needs – this needs to be addressed.”

Councillor Louise Gittins, chairwoman of the Local Government Association’s children and young people board, said: “It is vital the Government and NHS work urgently with councils to ensure the right provision is available for children, while we continue to call for a national commissioning service for secure children’s homes, with around 50 children each day waiting for a place in secure accommodation.”