The number of young people having to wait more than a year for NHS mental health support has more than doubled in the last year, according to official figures.

More than 200 children and young people were still waiting to be seen for treatment after 12 months, and thousands are waiting for longer than they should. Meanwhile while one in five of those referred to child and adolescent mental health services (CAMHS) are turned down.

Nine out of 14 health boards failed to meet the Scottish Government's target of treating 90 per cent of those referred within 18 weeks, according to the latest waiting times figures.

Children's organisations said "transformational change" was needed, describing Scotland's mental health crisis as an "epidemic" which often begins in the teenage years.

NHS Boards failing to meet the 18 week target are Fife, Grampian, Highland, Lanarkshire, Lothian, Tayside, Ayrshire and Arran, Greater Glasgow and Clyde Valley and Forth Valley.

The Scottish Children’s Services Coalition (SCSC), an alliance made up of private and voluntary sector children's service providers, said only 0.56 per cent of NHS Scotlnd's expenditure goes to fund CAMHS and that youth services make up less than seven per cent of the mental health budget.

However 50 per cent of mental health problems are established by the age of 14 and 75 per cent by the age of 24.5, the coalition claims.

CSCS is calling for an urgent focus on prevention and early intervention and a major increase in investment in mental health services. It also said the Scottish Government should address a postcode lottery for mental health treatment across the country. Although the 2018 Programme for Government announced an additional £250 million of funding, the coalition said more investment was still needed.

Meanwhile it said many of the 21.9 per cent of young people who are rejected for treatment had no real understanding of should happen next. It said effective early intervention services such as school-based resilience classes and better straining for education staff could reduce the need for referral to under-pressure specialist CAMHS.

A spokesperson for the SCSC said: "We are continuing to fail thousands of children and young people with mental health problems, with more clearly needing to be done to address this epidemic.

“These newly released figures highlight that the NHS in Scotland, including nine of our health boards, are failing to meet what is already a lengthy waiting time. Yet we know that three children in every classroom has a clinically diagnosable mental health problem.

“There must be a radical transformation of our mental health services, with a focus on preventing such problems arising in the first place and intervening early, especially when we know that half of all mental health problems begin before the age of 14. This includes embedding mental health within education from an early age as well as providing training for all staff involved in education.

“With mental health and the issues associated with it representing one of the greatest public health challenges of our time, we must ensure that children and young people are able to get the care and support they need, when they need it.”

In response, Billy Watson, Chief Executive at Scottish Association for Mental Health (SAMH), said it was unacceptable that so many young people in Scotland were not getting access to the mental health support they need.

"Young people are being rejected from mental health services across Scotland and families are being left unsupported. “Eighteen months ago, Scottish Government accepted all the recommendations in a major report on rejected referrals. Since then, over 9,000 young people have been told they won’t receive help. While we recognise that the Scottish Government is taking steps to develop services in this area, more needs to be done," he said.

Alex Cole-Hamilton, Scottish Liberal Democrat health spokesperson, said help was arriving too late for man young people: "Just last week the government denied there was a mental health crisis. Today, the length of time children and young people are waiting for treatment is the worst on record," he said. "The SNP Government is failing a generation of young people and the consequences of their waiting up to two years for treatment are heartbreaking."

Scottish Greens Parliamentary Co-Leader Alison Johnstone MSP called for a review of child and adolescent mental health services. She said: “Despite the fact that referrals to CAMHS have decreased over the past year, services are still struggling to treat people on time. When young people in distress cannot access treatment when they need it, something has gone terribly wrong.

“The Scottish Government needs to review this situation urgently .”

Mental Health Minister Clare Haughey said: the Government was making significant changes to meet increasing demand and claimed CAMHS staffing had increased by 74 per cent.

“We want to make sure anyone who has identified as needing support can get services that are appropriate to their needs," she said. "This includes the roll-out of our £250 million package of measures to support positive mental health for all.

“We are also strengthening the support available in communities and schools with mental health first aid training for local authorities, ensuring every secondary school has access to a counselling service by September 2020 and training 250 additional school nurses over the next three years, with 50 already in place this year.”