The number of referrals to specialist child mental health services has increased by 26% over the last five years, research by the Education Policy Institute has found.

Despite the increase, rejection rates for treatment have remained high since 2013, the think tank said.

It made freedom of information requests to 60 child and adolescent mental health services (CAMHS) and received 54 responses.

At least 55,800 children – as many as one in four referred – were denied treatment in 2017/18, the data revealed.

According to the Institute’s reportmany young people, including those who have self-harmed or who have been abused, were denied treatment because their conditions were deemed not serious enough to meet the eligibility criteria.

The report identified ‘strong exclusion criteria’ among some providers, including services that only accepted self-harm referrals if accompanied by a second mental health condition.

Some services required users to provide evidence that they had engaged first with early intervention services, such as schools and GPs.

But the data revealed that a quarter of local authority mental health support services, including those in schools, family counselling and domestic abuse services, had been ‘phased-out’ because of cuts to local authority spend on early intervention and preventative services.

The ‘real number’ of rejected referrals to children’s specialist services is likely to be higher, the report said, because ‘a number’ of providers did not disclose their figures and ‘most’ do not follow up with children that have been denied treatment.

There is also a ‘significant’ postcode lottery for access to treatment, with many areas lacking sufficient alternatives for young people who do not meet the threshold for treatment in a specialist service, the report warned.

Those who do qualify face ‘unacceptably’ long waits for treatment which vary greatly between services, and waiting times are twice as long as the four-week standard the government proposed in its children’s mental health green paper last year, the report said.

On average, children in London experience the longest wait for specialist treatment – 64 days – while those in the south of England wait 58 days.

The think tank said ‘loopholes’ in the CAMHS data reporting system had led to ‘many’ specialist providers not reporting ‘basic’ information about patient access, which made accurately assessing the quality of service provision difficult.

Further, it said privatised child mental health services ‘pose a barrier to transparency’ around publicly funded services because they do not have to report data under the Freedom of Information Act (FOI).

The report said the government should ‘look again’ at the FOI exemption applied to private providers offering publicly funded services.

Sean Duggan, chief executive of the Mental Health Network, part of the NHS Confederation, said: ‘It is essential we support the mental health of our children and young people – if we don’t then we will fail a generation.

‘This report again makes plain the challenges for mental health providers, with increasing demand and stretched resources.

‘Services are lacking the funding they need. We have the opportunity to put things right through the long term NHS investment plan – which is why it is vital that mental health gets its fair share of this funding.’

Councillor Anntoinette Bramble, chair of the Local Government Association’s children and young people board, said the report reinforced ‘the urgent need for a root-and-branch overhaul of children’s mental health services, and for the NHS to work with councils to develop a system that says yes, rather than no’.

A Department of Health and Social Care spokesperson said the government was investing £1.4bn in children’s mental health services, giving an extra 70,000 children a year access to specialist care by 2020/21.

‘We are improving access to mental health services through schools with a brand new dedicated workforce, as well as piloting a four week waiting time standard in some areas so we can better understand how to reduce waiting times,’ the spokesperson added.