(CNN) Metallica says it is postponing its tour in Australia and New Zealand after lead vocalist James Hetfield reentered rehab.

The heavy metal band made the announcement Friday in a series of tweets

"As most of you probably know, our brother James has been struggling with addiction on and off for many years," the band's tweet said. "He has now, unfortunately, had to re-enter a treatment program to work on his recovery again."

We fully intend to make our way to your part of the world as soon as health and schedule permit. We'll let you know as soon as we can.



(3/6) — Metallica (@Metallica) September 28, 2019

The band members said they planned to make their way to Australia and New Zealand "as soon as health and schedule permit."

"Once again, we are devastated that we have inconvenienced so many of you, especially our most loyal fans who travel great distances to experience our shows," the band's tweet read. "We appreciate your understanding and support for James & thank you for being a part of our Metallica family."