Childline has received a record number of calls from children who are feeling suicidal, the NSPCC has said.

According to the charity, last year its phone line had a call every 30 minutes from a suicidal child, with 19,481 young people receiving help from the NSPCC for suicidal thoughts.

"The top three concerns young people were counselled about were low self-esteem/unhappiness, family relationships and bullying/online bullying," the report said. "There was a 19% increase in low self-esteem/ unhappiness this year, so it replaced family relationships as the top concern."

And despite the charity reporting it had seen an increase in the number of young people using Child and Adolescent Mental Health Services, many said they did not receive helpful support and had been too scared to be honest with those providing counselling services.

This year, the government announced an extra £1bn ($1.3bn) would be invested in mental health by 2021, with one of the investment aims being the provision of mental healthcare to 70,000 more children and young people.

But the Childline report cited lack of access to mental health support and services as one of the issues young people had spoken to them about.

"We've seen an 87% increase in the number of counselling sessions where children and young people talked to us about struggling to access appropriate professional support locally especially for mental health problems, some of which were linked to their experiences of abuse," the report said, adding it had also seen an increase in the most serious mental health problems.

Children were also increasingly dealing with problems they encountered online – from bullying to grooming and sexual abuse, prompting the charity to increase its internet presence.

A Department of Health spokesperson said: "We have made huge strides in the way we think about and treat mental illness — moving from a society that locks people away in asylums to one giving mental health equal priority in law — but we must do more.

"It is positive that more people feel able to discuss their mental health, but this must be matched by the right support, which is why we are investing a record £1.4bn to help young people in every area of the country before they reach crisis point."