Applications for permits to shoot pornography in Los Angeles have fallen by 90%, since the use of condoms was made mandatory earlier this year.

The ordinance, passed in November 2012, made condom use a requirement for a permit in LA County, and banned the filming of bareback sex in the city, which has traditionally been a haven for porn studios.

However, despite the huge fall in official shoots, it is likely that the regulation simply forced studios underground.

Mark Kernes of industry magazine Adult Video News said: “A lot are simply shooting in out-of-the-way places where they won’t be caught.

“Normally it’s in people’s homes who are willing to rent them out for a day. Sometimes it’s out in the woods. There are vacation cabins far away from anything that you can shoot a movie at.”

Film LA, which issues the licenses, said that just 20 had been issued this year so far.

Steven Hirsh of Vivid Entertainment Group told Associated Press that his company may relocate if the law is not overturned.

He said: “There are several places we’re looking into. Some people are already shooting in Nevada, and that’s something that’s certainly on our radar.”

The AIDS Healthcare Foundation, which spearheaded the law, said: “When we first proposed the Los Angeles City bill, the industry said they’d film in other L.A. cities. When we proposed Measure B for L.A. County, the industry said they’d film in other counties.

“And when we proposed AB 1576, the industry said they’d film outside of California. Are workers in Nevada any less entitled to protection from harm than those in California?”