He's part of the same group of celebrities that were investigated along with Lee Soo Geun and Tak Jae Hoon for illegal online sports gambling. He was confirmed to have been summoned by the prosecutors to be investigated.
So far, Tony An or his label could not be contacted. However, his variety show 'Handsome Boys of the 20th Century' said, "We didn't know about Tony An's controversy. He hasn't yet said anything about leaving the show."
Source: Sports Chosun, Korea Economy, Newsen