Sex roulette parties where one person is secretly HIV positive and nobody is allowed to use condoms are on the rise, warn doctors.

The parties are usually attended by gay men, who are entertained by the 'thrill' of not knowing whether they will be infected or not.

Spanish doctors have noted a rise in the parties where attendees often take anti-viral drugs to reduce the risk of transmission.

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Sex roulette parties where one person is secretly HIV positive and nobody is allowed to use condoms are on the rise, warn doctors (stock image)

Dr Josep Mallolas of Hospital Clinic Barcelona said that the parties are a sign that people have 'lost respect' for HIV, reports el Periodico.

'There is everything: sex roulette parties, or sex parties you can only attend if you already have HIV,' he told the outlet.

He added that some of the parties are known as 'blue' parties because attendees take anti-viral medication to cut the risk of transmitting the virus.

Psychosexual therapist Kate Morley told HelloU: 'Going to sex roulette parties is about the risk, partygoers think the higher the risk, the stronger the thrill.

'In the case of sex parties the intense high is as you combine orgasm with high adrenaline.'

She advised, though, that the long term consequences are dangerous.