Children’s social services are under enormous pressure as they struggle to cope with increasing workloads, according to Ofsted’s annual report.

It found that one in three of the 10 local councils inspected this year, including Birmingham and Sandwell, were failing to keep children and young people safe.

Inadequate authorities were a “real cause for concern”, the watchdog said.

The inspectorate warned that social services were facing “significant challenges”, with more public scrutiny on what councils were doing to keep children safe than ever before. At the same time there has been a rise in demand for social workers’ time.

But many councils are facing staff shortages, and heavy case loads mean children are forced to wait for the help they need.

Between March 2009 and March this year, there was an 11 per cent rise in referrals to children’s services,

The number of initial assessments increased by 12 per cent and the number of children subject to child protection plans rose by 4.7 per cent.

The rise in demand has come after several high-profile child protection cases, including that of Baby Peter.

The report says: “Significant challenges face social care services in many local authorities from several sources. Public and media scrutiny of safeguarding issues has never been greater.

“There is pressure to bring about improvement.”

It adds: “Staff shortages are a problem in many areas and the problem of heavy workload emerges again and again. Children can wait too long for the response they need as a result of high caseloads.”

According to the national social work survey, 64 per cent of social workers said they did not have enough time to spend with the children and young people assigned to them, Ofsted noted.

Of the 29 local authorities inspected, around one in three was not keeping children and young people safe.

The 10 authorities whose children’s services were rated inadequate for safeguarding issues this year are Birmingham, Cornwall, Warrington, Leeds, Sandwell, Calderdale, Peterborough, Nottinghamshire, Salford and Essex.