The Mayor of San Francisco, Gavin Newsom, has been mocked after commemorating a studio that produces gay pornography.

Newsom honoured the 40th anniversary of Colt studios by designating last Friday as “Colt Studio Day.”

The 39-year-old mayor gained international attention in 2004 when he instructed city officials to issue same-sex marriage licenses.

Around 4,000 were issued before the state Supreme court declared them void.

The Rev. Louis Sheldon, chairman of the Anaheim Traditional Values Coalition, ridiculed the announcement.

“San Francisco has proven yet again why they remain the mocked city of the country,” he said, according to pressdemocrat.com.

“No other major city in the nation has gone so far as to blatantly glorify a homosexual porn producer and company.”

The studio has produced gay pornography for nearly 40 years, and celebrated their anniversary with a gala at San Francisco’s War Memorial Building.

California Assemblyman Mark Leno and San Francisco Treasurer Jose Cisneros also issued proclamations honouring Colt Studio.

Conservative talk show host Bill O’Reilly mocked the commemoration of the studio on his show “The O’Reilly Factor.”

“There is not another city in the country that has ever had a ‘gay porn day’,” he said.

“And you wonder why your city is looked upon as a modern-day Sodom and Gomorrah?”

The COLT Studio Group (CSG) started making pornography in New York City in 1967 before later moving to San Francisco.