"Looking for men and women for no-strings attached sex, preferably no condoms?" reads the enticingly explicit message seemingly posted by a young Brazilian woman on popular meet-up mobile site Tinder.

In reality, though, the poster is not a sultry Brazilian redhead. Rather, the message has been sent by the ministry of health as part of an in-your-face AIDS prevention campaign.

Anybody responding to the invitation purportedly sent by "Alana" gets not a hot date but a phone screen warning message reading: "Attention, it is difficult to know who is an AIDS carrier. Enjoy yourself -- but take care. This is a campaign by the ministry of health."

With AIDS rates on the increase among Brazilian youngsters the government decided to launch its campaign using the Tinder and Hornet phone applications. The latter is popular with the gay community.

"Augusto," on Hornet, boasts: "Sex without shame, sex with no limits. I like unprotected sex."

Health Minister Arthur Chioro explained in launching the initiative that "we can no longer talk about at-risk groups."

"Anyone who has a sex life is vulnerable, hence the importance of using a condom and undergoing testing," he added in a speech Monday.

The past decade has seen a 32 per cent rise in the number of 15-to-24-year-old Brazilians infected with HIV, each year bringing some 39,000 new registered cases, ministry figures show.

The campaign has been generally well received with most users recognizing the risk they run in having unprotected sex with strangers.

Even so, one man was frustrated after finding he could not meet up with "Augusto," asking: "But who's the guy in the picture?"