Nearly seven in 10 lesbian, gay, bisexual and trans (LGBT+) people have been sexually harassed at work, but many feel unable to tell their employer due to a fear of being “outed” to colleagues, research by the Trades Union Congress (TUC) has shown.

The survey of 1,001 people across England, Scotland and Wales, published on the International Day Against Homophobia, Transphobia and Biphobia, reveals a “hidden epidemic,” Frances O’Grady, TUC General Secretary, said.

More than one in five LGBT people said they had been asked unwelcome questions about their sex life, such as how they had sex, or what their sexual “role” was. More than a quarter said they had received unwanted verbal sexual advances, such as suggesting they should have sex with someone of the opposite sex to “make [them] straight”.

Two-thirds did not tell their employer about the harassment, and of those, a quarter said it was because they were afraid of being “outed” at work.

“What we’re finding is that when people come out with their sexuality at work, people think it’s OK to ask very personal questions about their sex life,” Elly Gibson, a press officer at TUC, said. “It’s a really horrible situation.”

LGBT+ rights around the globe Show all 9 1 /9 LGBT+ rights around the globe LGBT+ rights around the globe Russia Russia’s antipathy towards homosexuality has been well established following the efforts of human rights campaigners. However, while it is legal to be homosexual, LGBT couples are offered no protections from discrimination. They are also actively discriminated against by a 2013 law criminalising LGBT “propaganda” allowing the arrest of numerous Russian LGBT activists. AFP/Getty LGBT+ rights around the globe Brunei Brunei recently introduced a law to make sodomy punishable by stoning to death. It was already illegal and punishable by up to 10 years in prison AFP/Getty LGBT+ rights around the globe Mauritania Men who are found having sex with other men face stoning, while lesbians can be imprisoned, under Sharia law. However, the state has reportedly not executed anyone for this ‘crime’ since 1987 Alamy LGBT+ rights around the globe Sudan Both male and female same-sex sexual activity is illegal under Sudanese law. Men can be executed on their third offence, women on their fourth Getty LGBT+ rights around the globe Saudi Arabia Homosexuality and gender realignment is illegal and punishable by death, imprisonment, whipping and chemical castration Getty LGBT+ rights around the globe Yemen The official position within the country is that there are no gays. LGBT inviduals, if discovered by the government, are likely to face intense pressure. Punishments range from flogging to the death penalty Getty LGBT+ rights around the globe Nigeria Both male and female same-sex sexual activity is illegal and in some northern states punishable with death by stoning. This is not a policy enacted across the entire country, although there is a prevalent anti-LGBT agenda pushed by the government. In 2007 a Pew survey established that 97% of the population felt that homosexuality should not be accepted. It is punishable by 14 years in prison Reuters LGBT+ rights around the globe Somalia Homosexuality was established as a crime in 1888 and under new Somali Penal Code established in 1973 homosexual sex can be punishable by three years in prison. A person can be put to death for being a homosexual Reuters LGBT+ rights around the globe Iraq Although same-sex relationships have been decriminalised, much of the population still suffer from intense discrimination. Additionally, in some of the country over-run by the extremist organisation Isis, LGBT individuals can face death by stoning Getty

A gay man said: “One member of staff asked if I ‘take it up the arse’, and when I said I was unhappy about being asked [I was] told I was ‘a flouncy old queen.’”

A lesbian reported overhearing female colleagues saying; “I wonder if she pervs on us”. While a bisexual woman said a male colleague commented that she “must have some great threesomes” with her "lucky" male partner.

LGBT+ women were more likely than LGBT+ men to be affected. More than a third reported experiencing unwanted touching, for example hands placed on their lower back or knee. While more than one-fifth reported experiencing sexual assault, such as unwanted touching of the breasts, buttocks or genitals, or attempts to kiss them, while one in eight LGBT+ women said they had been seriously sexually assaulted or raped at work.

Black and minority ethnic LGBT+ women (BME) fared even worse. More than half said they had experienced unwanted touching at work, almost half reported sexual assault and more than a quarter reported serious sexual assault or rape. Half of LGBT disabled women reported unwanted touching.

Sexual harassment and assault has a big effect on people's lives. Around one in six said it had affected their mental health and a similar amount said they had left their job because of it.

The TUC said the findings are "shocking" and employers must take a zero tolerance approach to tackle it.