A third of teenage pupils have thought about harming themselves, a new poll has found.

The survey of 13- to 17-year-olds, conducted by the charity Addaction, found that, of the 33 per cent who had thought about self-harm, 6 per cent did so "all or most of the time", 10 per cent "some of the time" and 17 per cent "rarely". 

The new research, which draws on responses from more than 8,500 pupils at schools in Cornwall, Kent and Lancashire, also found that 28 per cent had felt down or depressed on at least six days in the past month.

Meanwhile, 22 per cent felt overwhelmed or worried often or all of the time.

Broken down to show the difference between males and females, the findings show that nearly a third of girls (31 per cent) felt overwhelmed or worried compared with 11 per cent of boys.

Teenage girls were also more likely to consider harming themselves compared with boys, and more likely to have a close friend who self-harms, according to the public health charity.

Rick Bradley, who leads the Mind and Body programme at Addaction, said the findings offered "a clear indication that increasing numbers of young people are really struggling".

He added: "There is mounting evidence that adolescent life can be overwhelming for many young people, with data indicating it feels particularly tough for girls and young women.

"We must do more to address this, but it is difficult when schools and support services are stretched, and the threshold for childhood and mental health services has never been higher.

"It's not easy for young people today. In some ways they've never been more connected, but these interactions can carry a lot of pressure, especially through social media, with negative impacts on people's body image and self-esteem.

"We also know many young people struggle with academic pressures and the intensity of the education system. When you factor in changes in hormones, responsibilities and relationships, it can make teenage years really challenging.

"Our message to young people is, you're never alone. Don't be afraid to reach out for help if you are struggling."

A separate report last week highlighted the scale of mental health issues affecting children and young people across England. According to NHS Digital, one in eight (12.8 per cent) children and young people aged between 5 and 19 had a mental health disorder in 2017.

The research found that a third of schoolgirls with mental health problems had self-harmed or attempted suicide.