Melbourne, June 13 The multi-billion dollar adult film industry in the US has been left facing a storm after 22 porn actors were reported to have contracted HIV.

State health officials in California fear moviemakers may not be following regulations that require them to provide protection against the transmission of the disease on film sets.

The state Division of Occupational Safety was looking to begin a formal investigation after a woman recently tested positive for HIV just after shooting an adult film.

"Our concern is that we need to quickly get to the employer so that we can work with them to change their practices to ensure the proper safety measures are being taken to prevent the additional spread of HIV," The Daily Telegraph quoted agency spokesman Dean Fryer as saying.

Los Angeles County health officials revealed 22 cases of HIV had been confirmed in industry performers since 2004.

Dr. Jonathan Fielding, director of the Los Angeles County Department of Health, said there were "persistent reports" about reckless practices.

Fryer added: "There is no reason these infections should be occurring if these employers are following these precautions."

Producers had made condoms mandatory after an HIV outbreak in 2004 but following a rebellion from both actors and audiences, it was made optional.

Steven Hirsch, co-Chief Executive of Vivid Entertainment Group, one of the industry's largest filmmakers, said: "What happened was the talent didn't want to use condoms. As a result, we decided to go condom optional." (ANI)