LOS ANGELES (AFP) - A US man, accused of running a "revenge porn" website hosting over 10,000 sexually explicit photos as part of an extortion ploy, pleaded not guilty on Friday, a court spokesman said.

Kevin Christopher Bollaert, 27, entered his plea in court in San Diego, Ms Karen Dalton said.

He has been charged with 31 counts of conspiracy, identity theft and extortion over the racket, which allegedly earned him tens of thousands of dollars.

Judge David Szumowski set a preliminary hearing for March 17.

His lawyer did not immediately respond to a request for comment.

Bollaert, who is free on US$50,000 (S$63,716) bail, was arrested last month.

He allegedly created the website ugotposted.com in December 2012, allowing explicit photos to be posted without the subject's permission.

The website "turned their public humiliation and betrayal into a commodity with the potential to devastate lives", California's Attorney General Kamala Harris said at the time.

The photos, commonly known as revenge porn, are typically obtained consensually during a relationship but then posted without permission, or are simply stolen or hacked.

Unlike other revenge porn websites where photos are anonymous, ugotposted.com required the poster to include the subject's full name, location, age and Facebook profile link.

Bollaert created a second website, changemyreputation.com, which he used when individuals contacted ugotposted.com asking for their photos to be removed from the site.

He then allegedly extorted victims by offering, from the changemyreputation website, to remove content from ugotposted.com for a fee of up to US$350, allegedly making tens of thousands of dollars, according to court documents.

"Online predators that profit from the extortion of private photos will be investigated and prosecuted for this reprehensible and illegal internet activity," Mr Harris said in a statement in December.

In October, California Governor Jerry Brown signed a law banning revenge porn.