Play video content EXCLUSIVE TMZ.com

1:15 P.M. PST -- Rob has released an apology, saying, "Please understand that although is it no excuse, I was completely unaware that in Australia there is a polarizing social issue happening right now involving indigenous people and alcohol. I'm sitting here in my hotel room completely gutted that a joke that I made was much more relevant to the times in Australia than I realized ... I feel like a fool and apologize to all Australians."

Rob Thomas found himself in a heap of trouble in Oz ... making a highly offensive remark towards Aboriginal Australians.

The former Matchbox 20 front man was in Melbourne Friday and when talking about his flight over says, "I drink til I think I'm Australian." Rob continues, "And then I keep drinking til I think I'm a black Australian." A big no-no considering the history and current struggle of alcohol abuse among natives.

You can hear a collective groan and even some boos from the crowd after the remark. We're guessing Rob didn't mean any harm, but one things for sure ... people were upset.