The 'True' hitmakers have hinted there were problems within the band and that the 57-year-old singer's departure has left the rest of them, brothers Martin and Gary Kemp, Steve Norman and John Keeble, with a feeling of great ''frustration''.
Responding to his abrupt exit, they wrote on their website: ''Much to our frustration, Tony had made it clear in September 2016 that he didn't want to work with the band anymore. This has not changed and 2015 was the last time we were able to perform or work with him. So we have now made the decision to move on as a band.
Spandau Ballet. (sic)''
Tony - who formed the pop group in 1976 with his bandmates -took to Twitter earlier on Monday (03.07.17) to announce his departure, insisting it was ''due to circumstances beyond [his] control''.
He wrote: ''I am no longer a member of the band Spandau Ballet & will not be performing with the band in the future. (sic)''
He also shared a note, which read: ''Due to circumstances beyond my control, it is with deep regret that I am required to state that I am no long a member of the band Spandau Ballet, and as such I will not be performing with this band in the near future. (sic)''
In July, Tony admitted he felt it would be ''best'' if they don't reunite, especially as they all have their own separate projects now.
At the time, he told BANG Showbiz: ''We are off doing our own things now and I can't see, certainly not for the foreseeable future, Spandau getting back together again. We have done a massive tour and I think it's best left.''
The group reunited in 2015 for a world tour and have split up on-and-off over their career spanning more than three decades.
Tony was the lead vocalist throughout the 80s, but his relationships with his bandmates hadn't always been plain sailing.
In 1999, Tony, drummer John and sax player Steve, all aged 57, were embroiled in a lawsuit over royalties with chief songwriter Gary, but they failed to sue him.