The state of mental health services for children in the UK is "alarming", a UN committee has told Government officials.
Waiting lists are too long, leading to an unacceptable situation, a member of the Committee on the Rights of the Child said as she questioned UK representatives in Geneva.
Olga Khazova of Russia hit out at a lack of funding and said she had heard one case of a child having to wait more than a year for proper treatment.
Government representatives were questioned on a series of issues looking at their commitment to promoting and protecting the interests of children.
Ms Khazova said: "I am sorry to say that mental health is an issue. Mental health services are underfunded, there is a trend to over-medication and therapeutic and community-based services are not developed. In many respects the situation is really alarming - again there are differences in different jurisdictions but this relates to all countries."
She said waiting lists for mental health care are "far too long and therefore absolutely unacceptable".
The four commissioners for children in Great Britain and Northern Ireland made 114 recommendations to the committee ahead of the hearing, including a section dedicated to mental health which includes a call to improve resources so children can be seen quickly.
Other issues included the possibility of lowering the voting age to 16.
Despite a call from the commissioners, Anne Jackson from the Department for Education said: "The UK Government has no plans to lower the voting age to 16. The Government believes that changes to the franchise should, where possible, be made on the basis of consensus and sees no majority across the United Kingdom in favour of lowering the voting age."
She added that it is "very important" for young people be involved in decision making and to be able to campaign for changes in the voting age.
The commissioners also recommended all forms of corporal punishment, including smacking, be made illegal - something supported by the NSPCC.
The Government has said while it does not condone "any violence" towards children and has laws to address such issues, it does not believe parents should be criminalised for "giving a child a mild smack in order to control their behaviour".
The two-day hearing will continue on Tuesday morning.
A spokeswoman for the Department of Health said: "Children's mental health is a priority for this Government and we know that intervening early can have a lasting impact. That's why we are putting a record £1.4 billion into transforming the mental health support available to young people in every area of the country. This will help make sure young people get the mental health support they need more quickly.
"This is the biggest transformation the sector has ever seen, with every local area in the country revolutionising their offer for children and young people through formal plans, backed with additional funding."