Dec 15 (Reuters) - A regional U.S. federal appeals courtruled on Monday that pornographic movie actors in Los Angelesmust wear condoms during sex scenes, upholding a lower courtdecision that was challenged by the adult film industry.

In 2012, voters in Los Angeles County approved a measure torequire condom use during sex scenes in pornographic movies, aswell as the regular testing of actors for sexually transmitteddiseases.

Lawyers for the industry challenged the regulations in U.S.District Court, arguing that the condom requirement went againsttheir clients' right to freedom of expression under the FirstAmendment of the U.S. Constitution.

Pornographic movie producers have said visiblecontraceptives put off some of their customers, because theyreminded them of real-world worries such as pregnancy anddisease.

A three-judge panel of the 9th U.S. Circuit Court of Appealsupheld the requirement on Monday, saying it was narrowlytailored to achieve the County's interest of reducing the rateof sexually transmitted infections while also leaving open"adequate alternative means of expression."

The panel said it agreed with the lower court that, whatever"unique message" the film makers might hope to convey bydepicting condomless sex, it was unlikely that viewers of adultfilms would understand that message.

Likewise, the San Francisco-based appeals court said,mandates to test actors, and to require producers to complete acounty-approved training course on blood-borne pathogens, servedthe goal of preventing sexually transmitted infections.

It noted that three adult film makers listed among theplaintiffs in the case already required performers to provideidentification and to submit to tests at least once a month.

Much of the U.S. adult movie industry, which is worth anestimated $9 billion to $13 billion a year, is based in LosAngeles County. The AIDS Healthcare Foundation has said actorsin pornographic films are 10 times more likely to contract asexually transmitted disease than the general public. (Reporting by Daniel Wallis in Denver; Editing by MohammadZargham)