A song so catchy it went viral, now the South Korean producers of the tune Baby Shark are having their day in court.

They are being sued by entertainer Johnny Only, who says he came up with his version of the song in 2011.

But the South Korean producers say they based their song on a popular campfire tune.

The case has been handed over to a copyright commission in South Korea to decide.

Al Jazeera's Rob McBride reports from Seoul.