One in 6 of all Childline counselling sessions focused on mental health issues last year – equating to one call every 11 minutes, the charity has said.
In 2015/16, Childline had 50,819 counselling sessions with children and young people worried about suicidal feelings, self-harm, mental health or depressive disorders.
The figures, announced to coincide with the start of Children's Mental Health Week, also revealed that girls were almost 7 times more likely to seek help than boys.
The sharpest increase in counselling sessions delivered over the past 4 years were for mental health and depressive disorders, up by 36%, Childline said. The number of children and young people receiving counselling for suicidal feelings also increased. More than a third of counselling sessions about mental health issues were with 12-15-year-olds.
Dame Esther Rantzen, president of Childline said: “It's striking how many more children seem to be suffering serious mental health problems today than when we launched Childline 30 years ago.
“So many desperately unhappy children seem to be suffering suicidal thoughts, self-harming, becoming anxious and depressed, with many of them turning to Childline because no other support is available.
“We know CAMHS are terribly overstretched, meaning that young people aren't able to access the professional help they need. We believe there needs to be far more emphasis on providing help for these children as they struggle to deal with what are very serious illnesses.”