Zac Efron 'nude picture' trends on Twitter

A nude photo of Zac Efron has been deemed a fake by users of Twitter, after it became the subject of a trending topic on the site.

A picture that appears to show the naked High School Musical actor has recently appeared online, but users have pointed out the exact similarities of an old photo of the star's, and have declared it as a fake.

"The awkward moment when people find out why 'Zac Efron's' trending and they actually believe the reason," has since become a top tweet on the site.

Another user wrote: "Just learned why 'Zac Efron's' is trending. Is it possible to un-see things?"

Blake Lively and Selena Gomez are among stars who have recently had to declare that nude photos of them are actually fake.

Ashley Tisdale recently denied claims that she was dating her High School Musical co-star Efron.

Efron has recently signed up to appear in a new R-rated comedy with Seth Rogen, where he will play a hard-partying college student whose frat house causes trouble for a nearby resident.