Not long after departing Megadeth's Sidewave shows, Newsted is cancelling concert dates through March -- including a scheduled appearance at the Soundwave Festival in Australia. Details on just why remain sketchy.

Frontman Jason Newsted, the Metallica alum, is telling fans via Facebook that the decision is due to "private and personal circumstances ... We are all gutted by this turn of events. Our hope is that we will have another opportunity to share our heavy music with you all again sometime in the near future. I'm sorry, sisters & brothers, We were really looking forward to these shows too."

As recently as last week, Newsted had posted a positive update on rehearsals for these upcoming performances. Whether the Sidewave and Soundwave cancellations are related is unknown thus far.

Megadeth, which is led by another ex-Metallica man in Dave Mustaine, was at first rumored to have removed Newsted from the Sidewave performances earlier this month. A band rep later denied the charge, and Megadeth also pulled out of the shows as part of the fallout.