United Kingdom, June 11 -- Billy Ray Cyrus' son Trace Cyrus has called his dad the "lamest man ever to walk planet earth" in a scathing social media rant.

The musician - who is the brother of pop star Miley Cyrus - blasted his father in a post on Instagram in which he claimed Billy Ray skipped the funeral of Trace's beloved grandmother Loretta Finley - known as Mammie - five years ago because he didn't want to fly to Los Angeles and Trace pointed out the Achy Breaky Heart singer had recently made a trip to Italy for a holiday with his girlfriend Elizabeth Hurley.

In a post on Instagram, Trace wrote: "This man is so hungry for fame it's pathetic. He really flew to Italy for a fashion show but wouldn't come to LA for Mammie's funeral whil...