Almost half of British teenagers who are LGBT or questioning their sexuality have self-harmed, according to a study released on Wednesday that found they have significantly lower life satisfaction than their peers.

Homophobic bullying and "highly gendered" environments were adding to pressure on young people struggling with their sexuality, according to the report from The Children's Society.

"There's still an awful lot of stigma," Richard Crellin, policy and research manager at the charity, told the Thomson Reuters Foundation.

"There are still too many schools where being called gay is an insult, where there isn't an inclusive atmosphere, and young people might feel like they need to hide their sexuality because they might be bullied by staff or by pupils."

Although Britain is one of a handful of countries where LGBT people have equal constitutional rights, activists say young people often face intense pressure over their sexuality.

Nearly half of LGBT pupils face homophobic bullying in school, according to a report by charity Stonewall last year.

Last week, a nine-year-old boy killed himself after facing intense homophobic bullying at his school in the U.S. state of Colorado, local media reported.

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"Four days is all it took at school," his mother Leia Pierce told the local news station KDVR. "My son told my oldest daughter the kids at school told him to kill himself."

The Children's Society report found a wide gulf between the happiness of teenagers who experienced same-sex attractions and those who did not, in an analysis of data collected from about 19,000 14-year-olds in 2015.

More than a quarter of LGBT or questioning teenagers were found to have low life satisfaction, compared just over ten percent among all respondents. Almost 40 percent had high depressive symptoms.

Just over 15 percent of all the children surveyed said they had self-harmed in the previous year, a figure that rose to nearly half among those who reported same-sex attractions.

LGBT charity Stonewall said both parents and schools should take action to ensure children were supported.

"When bullying is not tackled it can have a deeply damaging and long-lasting effect on young people," said a spokesman.

"We would encourage schools who want to help support LGBT students to ensure that there are no tolerance policies on this specific type of bullying."