Ward refused to be a part of the Sabbath reunion in 2012 following a series of unresolved contractual disputes and frontman Ozzy has since questioned his former bandmate's abilities.

The dispute rumbled on as Osbourne,Tony Iommi and Geezer Butler recorded a new album, 13, and hit the road for a global tour - and there is now talk of a farewell album and one more live trek, which many fans would like to see Ward a part of.

But the drummer has ruled out a return to Black Sabbath unless Ozzy agrees to make amends for what he has said.

In a new statement he says, "I have neither severed nor discontinued my relationship with Black Sabbath, however, since 2012, the often inaccurate statements about me as a person and as a musician have caused me to be guarded and be especially detached emotionally and spiritually from Ozzy. His rhetoric above all has brought me the most discord.

"With a sad heart, I have to say I will not participate in any musical undertakings until a righting of the wrongs spoken against me has been achieved. I have little to no expectations of this happening, but, in the order of first things first, I’m looking for an honest accountability of all of Ozzy’s statements that I felt were untrue.

"I would want Ozzy to amend his opinions and exaggerations. I would want him to be forthcoming about his unrealistic viewpoints. And, because I was chastised publicly, I would want him to amend publicly in his words, and not through an Ozzy representative, the nature of the wrongs."

He adds, "I don’t think previously strong relationships can remain strong after dispute by just sweeping the offensive stuff under the carpet, or by saying a puny 'Sorry', or, 'Oh, that's all over now'. Righting of wrong works - and that’s what I want if I'm ever going to be his friend again."

Ward admits he's sorry his dispute with his former bandmates may have upset Sabbath fans: "I love you all dearly. You f**king rock. I have been in deep regret that a true union was denied. I’ve remained faithful to you and honest with myself. Had I not been honest throughout I would have perished long ago. Stay safe and stay strong."