The homemade music video, titled "Happy We Are from Tehran", was uploaded to YouTube last month. It shows the fans dancing around on a rooftop and in a private flat to the beats of Pharrell's eponymous upbeat tune.

"We have made this video as Pharrell Williams' Fans in 8 hours, with iPhone 5S. "Happy" was an excuse to be happy. We enjoyed every second of making it. Hope it puts a smile on your face," reads a message at the end.

The video was part of a global phenomenon that has seen hundreds of covers of Happy uploaded and promoted on YouTube, Instagram and Facebook feeds across the world.

The Pharrell fans appeared on state TV in Iran yesterday to confess to making the video, which Tehran's police chief Hossein Sajedinia described as "obnoxious".

"We launched a police investigation in cooperation with the judicial authorities and identified and arrested the accused within six hours," he told Iran's official news agency Isna.

Young Iranian fans arrested over Pharrell Happy video