'Inadequate' children's services outnumber the 'good'
Up to a quarter of children's services in English councils face being taken over unless improvements are made, Ofsted has said.
It comes after the latest inspection figures revealed there were more "inadequate" ones than "good".
Councils rated as "inadequate" face having children's services handed to charities or other authorities if they do not improve.
One council leader called for a review of Ofsted's inspection criteria.
The call came after fewer than a quarter of children's services inspected in the past two years were judged "good".
Only 17 out of 74 council children's services were good and none was outstanding. The other 38 across England "require improvement".
About half of councils have been inspected under new Ofsted criteria introduced two years ago. The education watchdog said the results were "not necessarily representative of the quality of services for all local authorities in the country" until reports for all the others were done.
But they suggest that councils will find it harder to satisfy inspectors than those inspected before November 2013.
Figures showed that out of the nine English regions, the South West did not have a single local authority children's services department rated "good" among seven inspections since the end of 2013. Another nine have yet to be inspected under the new criteria.
The North West and the South East each have four "inadequate" children's services, while the West Midlands and North East have three and all other regions have one.
Councils judged inadequate for 'overall effectiveness' of children's services:
Birmingham; Buckinghamshire; Coventry; Cumbria; Darlington; Doncaster; Knowsley; Lambeth; Lancashire; Leicester; Manchester; Norfolk; Rotherham; Sandwell; Slough; Somerset; Sunderland; Surrey; West Berkshire
Prime Minister David Cameron has said failing departments have to improve within six months or they will be taken over by high-performing councils or charities.
However the Labour leader of Sandwell Council, which has had two successive "inadequate" ratings and will see commissioners sent in within a year, has called for a re-think of the inspection criteria.
Councillor Darren Cooper said: "When the figures show there are more 'inadequate' councils than 'good' ones and that none are outstanding, something is obviously wrong.
"There must be a pause for reflection and a re-think."
He said the council was working to address the criticisms made in the Ofsted reports but that officers and councillors had been given expert advice that they had improved before their last poor rating in June 2015.
But Conservative MP James Morris, whose Halesowen and Rowley Regis constituency covers part of Sandwell, said: "When protecting our most vulnerable children, we need to make sure that we have the most rigorous safeguards in place. The Ofsted report into Sandwell highlighted some very serious flaws. We need to make sure that we sort this out now, rather than looking for excuses to delay change."
The new "single inspection framework" sees inspectors judge child protection and services for looked-after children at the same time in one report. Ofsted said the harder test asked what difference services were making to children's lives.
That framework "has undoubtedly raised the bar," according to Ofsted.
"While we accept it is tough to achieve a good or better grade, children deserve no less than a good standard of support from those charged with caring and protecting them," a spokesman for organisation said.
"Inspectors have seen examples of good and outstanding practice in several local authorities and this is reflected in their overall inspection outcome."
In a statement, the Department for Education vowed "to take tough action where councils are failing children" highlighting "over 30 securing real improvement as a direct result of our intervention since 2010".
It continued: "We must now go further... We will also be partnering with the best local authorities, investing £100m in innovative support to local authorities, as well as investing £100m in fast track social work training."
Children's homes improve
Ofsted inspected 959 children's homes between April and September 2015 and found 71% were good or better, an improvement of 13 percentage points on the year before.
But of the 71 homes previously inspected as "outstanding", 29 of them declined to "good", two declined to "requires improvement" and one declined to "inadequate".
The figures showed the South West had the largest number of "inadequate" rated children's homes, 14 in total.