The Home Office “must ensure” caseworkers do not ask gay asylum seekers “sexually explicit questions”, the Independent Chief Inspector of Borders and Immigration has warned.

A review by Sir John Vine has been published today in Parliament.

The Chief Inspector expressed particular concern about the treatment of sexual identity cases in the Detained Fast Track (DFT) process.

Earlier this summer, the High Court ruled that fast track detention, a system used to process the vast majority of cases, was “unlawful”.

Sir John found there was inconsistent practice between teams dealing with detained and non-detained applicants. DFT accepted sexually explicit material submitted as evidence, whereas the non-detained areas did not.

The review revealed unsatisfactory questions were more than twice as common within the DFT and included questions likely to elicit sexually explicit responses or querying the validity of same-sex relationships.

In more favourable language, the Home Office’s guidance and training on asylum cases based on sexual orientation was described as “concise and clear”, and that “most asylum interviews complied with guidance.”

However, the guidance was not being applied consistently and unsatisfactory questions were found in a sample of cases.

A fifth of interviews contained some stereotyping and a tenth contained questions of an unsatisfactory nature.

Management information on sexual orientation claims was also described as “inadequate” by the review and only around a third of sexual orientation cases had been recorded as such, so the Home Office had under reported the incidence of these cases; and the allowed appeal rate for DFT sexual orientation decisions was over double the rate for DFT asylum claims as a whole.

Home Secretary Theresa May ordered the review by Sir John in March, following a leaked report published by The Observer revealing that LGBT asylum seekers continue to face degrading “interrogations” about their sex lives by Home Office staff.

It was claimed one bisexual man underwent five hours of questioning with no lawyer present.

Questions allegedly included: “Did you put your penis into x’s backside?” and “When x was penetrating you, did you have an erection? Did x ejaculate inside you? Why did you use a condom?”

The man was also asked: “What is it about men’s backsides that attracts you?” and “What is it about the way men walk that turns you on?”

Commenting on his review, Sir John Vine said: “Asylum applicants, particularly those in fear of persecution based on their sexuality, are often vulnerable individuals.

“I was pleased to find that guidance and training for caseworkers was generally clear and concise and dealt with difficult and sensitive areas of questioning. I did not find any questions of the type highlighted in the Observer article, but over a tenth of interviews did contain questions of an unsatisfactory nature.

“Such questions are not acceptable and the Home Office must work to eradicate them. I did not, however, identify any direct correlation between inappropriate lines of questioning and the likelihood of a claim being refused.”

Sir John continued: “I was concerned to find differences in the way DFT cases were handled, with more likelihood of unsatisfactory questions being asked and sexually explicit material being considered as evidence. The allowed appeal rate in these cases was also over double that of DFT’s asylum claims as a whole.”

He concluded: “I have recommended that the Home Office ensures that caseworkers do not ask sexually explicit questions, and equips them with the interviewing skills to cope professionally when sexually explicit responses are received.”

The Chief Inspector made eight recommendations for improvement. These included that the Home Office should ensure a consistent approach towards the handling of explicit material presented to support an asylum claim, and that all asylum claims made on grounds of sexual orientation should be accurately recorded as such.

The DSSH (Difference, Stigma, Shame, Harm) model, which was created by barrister S Chelvan should be used to train caseworkers, the report recommended.