Austrian authorities on Friday said they were investigating 17 teenagers -- including 12 minors -- over the alleged months-long sexual abuse of a 12-year-old girl in Vienna last year.

The alleged offences took place in a disadvantaged area of the capital's south "between February and June 2023, in toilets, garages, a hotel and in the perpetrators' homes", Florian Finda, deputy director of the Vienna police, told a news conference.

The suspects in the rare case -- most of whom are aged between 14 and 18 -- are of Bulgarian, Italian, Serbian, Syrian and Turkish origin.

Two of them are under 14 and therefore below Austria's age of criminal responsibility.

The suspects -- almost all of whom were known to police for other offences -- are accused of serious sexual abuse of a minor, including the pornographic depiction of the abuse of a minor.

Thirteen suspects were questioned on Thursday, with some of them partially denying the allegations.

The suspects and the Austrian victim met through one of the accused, with whom the then 12-year-old is said to have made out with.

She was then introduced to the rest of the group.

The boys allegedly exchanged videos and photos of the abuse via social networks including WhatsApp chats, with one of them allegedly threatening to share the pornographic material.

According to the police, none of the material was made available to the wider public.

In October, the young girl, now 13, informed her mother, who subsequently filed a complaint.

The ongoing investigation is due to be transferred to the public prosecutor's office.