A mother whose 10-year-old daughter suffers severe mental health problems and has tried to commit suicide has complained to David Cameron about the NHS's failure to provide her family with proper help.

Sam Lethbridge also told the Prime Minister how a Jewish primary school dealt with her daughter's problems by "locking her in a small room and removing her tights and socks in case she tried to strangle herself".

Mrs Lethbridge, 38, sent an open letter to Mr Cameron, detailing the anguish and frustration that she and husband Jonathon, 42, have faced in trying to help their daughter, who has a range of special needs and mental health issues.

Over the past five years, their child - who they do not wish to name - has gone from "sparky and sociable" to suffering from severe depression, sleep deprivation and suicidal tendencies.

According to her mother, she experiences regular "meltdowns", which can turn violent and aggressive. The young girl's life has been blighted by a catalogue of serious problems, among them ADHD, Asperger's syndrome, anxiety, depression and dyslexia.

The first signs of problems appeared when the girl was five and struggling to read and write. She was eventually referred to a paediatrician who diagnosed the ADHD and sleep disorder.

After just three sessions with a nurse from the Child and Adolescent Mental Health Service (CAMHS) the child was discharged.

Subsequently her condition deteriorated. On one occasion, Mrs Lethbridge found her child with the cord of her dressing gown around her neck, threatening to kill herself. On another, her daughter came at her with a knife.

Despite the seriousness of their situation, the family, who are members of Shenley United Synagogue, said they have received almost no help from their local CAMHS.

In her letter Mrs Lethbridge wrote: "When we were eventually seen

by CAMHS they simply wanted to pump our daughter full of drugs. Drugs that have serious side effects. No one has spent any time talking to our daughter or offering the therapies supposed to be available."

According to Mrs Lethbridge, her daughter has been failed by the system which simply "ticks boxes".

She believed her daughter's problems were exacerbated by her former school, a Jewish primary in the London area. Writing to Mr Cameron, she said: "My daughter was seriously neglected at her first primary school. They had no understanding of special needs.

"Their solution was to lock her in a small room on her own. To remove her tights and socks in case she strangled herself. To leave her screaming and crying. She was eight-years-old." The child spent more than five years at the school, which the couple declined to name.

Their daughter was eventually hospitalised in a specialist psychiatric unit. Seven months later and after a significant improvement, the child was discharged - on the proviso that she attend a specialist school and receive ongoing support from Hertfordshire's CAMHS. But to this day, there has been no contact from CAMHS.

The family have had some support from within the community. Norwood have been "fantastic", as has Wolfson Hillel Jewish Primary School, where their daughter was briefly moved to before she was hospitalised.

The family have been forced to sell their home in Shenley, Hertfordshire, and move to rented accommodation in Borehamwood. "We were so stressed that we lost track of our finances," said Mrs Lethbridge, who runs an online support group for more than 900 families in situations similar to theirs.

"It's been so hard, but we're the lucky ones. We're strong and we fight. It's brought us closer together, but not everyone is in our situation."

Mrs Lethbridge told Mr Cameron that mental heath services were failing the nation's youngsters. She wrote: "Our children are broken. The system for children's mental health is in crisis. I liken it to an open wound. You wouldn't send a child home from hospital with an open wound that was bleeding profusely. Well, my daughter is an open wound and she is bleeding."

The family's MP, Oliver Dowden, has raised the issue with the NHS. He said: "I am determined to do everything I can to support them in getting the best care and support for their daughter."

Paul Lumsdon, director of service delivery and customer experience at Hertfordshire Partnership University NHS Foundation Trust (HPFT) said: "We are sorry to read of the issues raised in Mrs Lethbridge's open letter and sincerely apologise to the family if the services accessed have not supported them in the way they would have liked.

"We will review the contents in depth and take some key learning from this to ensure this unfortunate situation does not occur again."

Alistair Burt, the minister for mental health, said: "I was moved by Mrs Lethbridge's story and I know we've got more to do."