Dozens of children with mental health problems are being treated on adult psychiatric wards despite the practice being banned, it has been reported.
New figures are said to also show the number of under-18s receiving treatment with adults potentially suffering from severe psychiatric problems is expected to rise, with hundreds receiving treatment in adult environments.
Health Secretary Jeremy Hunt said the number of children treated in adult psychiatric wards has fallen by over 60% since the coalition government came to power in 2010 and that investment is increasing.
However there are still many cases of children being placed on adult wards - a potentially traumatic experience - despite the practice being forbidden under rules brought in under Labour, according to The Guardian.
Data released to the newspaper by NHS Digital showed 260 under-18s were treated with adults between January and July this year.
There were 39 children aged 15 or under, 90 16-year-olds and 131 17-year-olds over the period, although some may have appeared in the figures for more than one month, The Guardian said.
The Mental Health Act stipulates that "the patient's environment in the hospital is suitable having regard to his age (subject to his needs)".
In exceptional circumstances, such as an emergency, 16 and 17-year-olds can be treated on adult wards, but under-16s should never be admitted to an adult ward.
The NHS data suggests around 450 children and young people will pass through adult psychiatric wards in 2016.
In 2014-2015 a total of 391 youngsters were treated on adult wards, with most cases in the north of England.
The total number of beds in children and young people's mental health services has increased to 1,442, according to Department of Health figures.
Mr Hunt said: "The number of children in adult psychiatric wards has gone down by over 60% since 2010.
"However this type of care should be an absolute last resort, once all other avenues have been exhausted -- but to help ease demand, we recently opened 50 new beds, increasing the total number to the highest there has ever been.
"We are investing £1.4 billion in children and young people's mental health over this Parliament, one of the largest investments the sector has ever seen, and have made more money available than ever before for mental health, increasing our investment every year since 2010 to a record £11.7 billion last year."