The Achy Breaky Heart star, father of singer/actress Miley Cyrus, was  to appear at the country music event in early March, but has pulled out for medical reasons.

Cyrus has not revealed the nature of his illness, but reports suggest he is suffering an ear condition.

Organisers of the festival have confirmed his departure from the bill and revealed they have added Australian country duo McAlister Kemp as a replacement.

"By now, most of you will have heard the sad news that due to a medical condition, Billy Ray Cyrus will no longer be able to perform at the festival,” a statement from CMC says.

“When we announced the news on Friday, we were inundated with suggestions for who should perform in his stead, and one artist emerged as a clear favourite – McAlister Kemp.

“The chart-topping local duo, made up of Drew McAlister and Hunter-area local Troy Kemp, are the biggest double-act in Australian country.  

“The Golden Guitar and CMC Music Award winners are veterans of CMC Rocks, winning more fans with each electrifying performance.

“Their latest album ‘Country Proud’, launched at CMC Rocks the Hunter 2012, has spawned hits including the anthemic title track and the cheeky Cold Beer, Hot Women. 

The fan-favourites will bring their rowdy charisma and boundless energy to the main stage on the Saturday night from 7.45pm to 9pm.”

The festival kicks off in the NSW Hunter Valley on March 15. 

Other artists on the bill include Rascal Flatts, Big & Rich and The Band Perry.

Head to www.cmcrocks.com.au for more information.