As we mark 50 years since the partial decriminalisation of homosexuality, LGBTQI+ people who seek sanctuary in Britain from persecution in other countries are subjected to invasive questioning and risk being detained indefinitely.

More than 70 countries in the world criminalise same-sex acts and many LGBTQI+ people are at risk from persecution for being who they are.

It is not unusual for LGBTQI+ people attending asylum interviews to be asked questions based on assumptions of what it is to be LGBTQI+, that focus on intimate details of their sexual conduct, or that re-traumatise individuals.

One person was recently asked what it felt like when they were being raped. Another was asked when they first had sex with their partner.

Others end up having to explain why they are not heterosexual. One man was recently told that the caseworker did not believe he was gay since some cross-dressers identify as straight.

The Home Office also puts some LGBTQI+ people seeking asylum into detention. Britain has one of the largest detention estates in Europe and, shockingly, is alone in detaining people for indefinite amounts of time.

At the UK Lesbian and Gay Immigration Group, we regularly visit people who have been detained for several months: people who have applied to stay in this country for fear of persecution — including beatings, rape and death — in their countries of origin.

Our joint research with Stonewall has found that in detention, LGBTQI+ people who are seeking asylum suffer discrimination, harassment and violence from other detainees.

People are made to share rooms with people who share similar prejudices and abusive behaviours to those they are trying to flee: people who are homophobic, biphobic or transphobic.

One person reported feeling as unsafe in the detention centre as they did in Pakistan.

“He was in the gallery and he called: ‘Hey! Mr Gay, I love you! I want to fuck you.’ I was so scared. I just went in my room. Here in detention it is the same as where I came from. I was so scared.”

Many have reported that detention centre staff have failed to act on such bullying. Detention can have serious effects on the physical well-being of LGBTQI+ people.

In detention, some have reported not receiving medication for heart conditions or HIV. Trans people on gender-affirming hormones are denied continued access to treatment, adversely affecting their mental and physical wellbeing.

The detrimental impact on mental health can also be long-lasting. LGBTQI+ people can suffer depression or panic attacks, or self-harm. Some detainees have attempted suicide.

After being released from detention, LGBTQI+ people seeking asylum often experience flashbacks, suffer memory loss or find themselves unable to sleep.

LGBTQI+ people are often excluded from communities from their countries of origin because of prejudice against them. Identifying and accessing LGBTQI+ support networks is challenging.

The experience of detention makes it hard for them to settle into society even when they have regained their freedom.

Detention can also restrict the ability of LGBTQI+ people to gather evidence in support of their asylum claims. LGBTQI+ people frequently need to provide evidence from witnesses in their countries of origin to testify to their sexual orientation or gender identity as part of their asylum applications.

In detention, they can find it almost impossible to contact people in their countries of origin discreetly to gather such evidence. Many of their contacts at home also fear persecution if they are associated with someone who identifies as LGBTQI+.

Restrictions on smartphones and social networking sites in detention can also stop LGBTQI+ people from gathering the evidence they need to pursue their cases and get written records of their past relationships.

Britain has made great strides in protecting and promoting the rights of LGBTQI+ people in the last 50 years. Our government also seeks to promote the rights of LGBTQI+ people in other countries.

Yet its treatment of people from those same countries who seek protection on British soil stands in sharp contrast.

LGBTQI+ people from countries where they are persecuted because of their sexual orientation or gender identity hope that Britain’s record in respecting human rights will protect them.

They want to enjoy the freedoms that other LGBTQI+ people in Britain enjoy. Yet often they encounter a system that refuses to believe they are LGBTQI+ or that they face persecution, and adds to their trauma by putting them into detention for an indefinite amount of time.

More training is needed of Home Office caseworkers so that asylum interviews treat people with dignity.

Decision-makers also need to be better trained in assessing sexual orientation in asylum claims. The government should also aim to issue guidance soon on gender identity in asylum claims.

The government should ensure that vulnerable people like LGBTQI+ asylum-seekers are not put into detention centres and that all immigration detention has a time limit of 28 days.

• Leila Zadeh is executive director of the UK Lesbian & Gay Immigration Group.