The Kids Helpline estimates it received 700,000 point of contact requests for help through its website and hotline last year, a jump of almost 10 per cent from a year earlier.

But a lack of funding and a rise in more complex and severe mental health problems means overworked counsellors are unable to cope with demand.

''Ten years ago people called us about single problems,'' Wendy Protheroe, general manager of counselling services at the Kids Helpline, said. ''Now the calls take longer and require much more in-depth advice.

''Counsellors are usually speaking to kids with mental health issues, family problems, suicide concerns and relationship breakdowns.''

Last year, the service's 135 counsellors dealt with an average of 26 young people a day who were considering suicide, a three-fold increase since 2006. About 43 children a day who were self-harming contacted the hotline.

The majority of counselling sessions were with female teenagers aged 13 to 18, with the average call lasting 34 minutes.

Senior lecturer in psychiatry at the University of Sydney Ramesh Manocha said a shortage of school counsellors and increasing stress and social pressure on children is contributing to the alarming rise in calls.

"Mental health support in schools is woefully inadequate," Dr Manocha said. "For every child in crisis there might be another 10 with serious problems, but school counsellors can only deal with the most severe situations.

"Our society has created the perfect storm of social risk factors. A culture that celebrates excessive drinking and materialism is setting up children to be more anxious and unhappy than ever before. We are not sending them the right messages."

The service, which costs about $11 million a year to run, received a total of 390,000 calls and emails to counsellors last year, but about 156,000 were unanswered. Counsellors held about 72,000 sessions, with 22 per cent responding to people deliberately harming themselves and 13 per cent dealing with suicide concerns.

Suicide was the most common cause of death among Australians aged 15 to 24 in 2012, with 214 boys and men and 110 girls and women taking their own lives.

The alarming rates of suicidal behaviour and self harm have prompted National Children's Commissioner Megan Mitchell to hold an inquiry into the problem to be presented to the Parliament this year.

Anyone seeking support can call Lifeline on 13 11 14 or the Kids Helpline on 1800 55 1800.