An AIDS support group announced legal action Tuesday against a US porn film company for allegedly failing to enforce a new Los Angeles law requiring actors to wear condoms while on set.

The AIDS Healthcare Foundation (AHF) accused Immoral Productions of violating the Safer Sex in the Adult Film Industry ordinance, passed by LA County lawmakers after voters backed the move in a November referendum.

AHF chief Michael Weinstein said he had received an anonymous letter alleging that the filmmaker had not posted signs on set to tell actors that condoms were required.

The group checked online footage streamed by the company, to verify that condoms were not used.

"Violations of the law are recorded and streamed live," said Weinstein, adding: "The threshold question here is whether the county is going to enforce this law."

There was no immediate response from Immoral Productions to a request for comment.

Fifty-six percent of LA County voters backed the condom rule, called Measure B, in a referendum in November, held at the same time as the US presidential and other ballots.

In January, a group of porn filmmakers -- which, in the US, is primarily based in the San Fernando Valley, north of LA -- filed a lawsuit in the opposite direction: suing the LA County over the new law.

Porn giant Vivid Entertainment, Califa Productions and actors Kayden Kross and Logan Pierce claimed the porn film industry already regulates itself sufficiently to protect actors against AIDS/HIV and other diseases.

It also violates the First Amendment right to free expression, they said.

California porn film-makers were forced to suspend production temporarily in 2011 after an actor tested positive for HIV, the virus which causes AIDS, in the latest such disruption to the multi-billion-dollar industry.

Film LA Inc., which issues permits for film companies shooting in and around the West Coast city, says about five percent of the 45,500 permit days the agency issues per year are for pornographic film shoots.

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[Woman opening condom via katielittle / Shutterstock]