According to Australia's Nine News network, Werdum, 40, has been charged with common assault. The Brazilian heavyweight is scheduled to face Marcin Tybura at UFC Fight Night on Saturday at Qudos Bank Arena.
Covington, 29, is in Sydney for the event, but he is not fighting on the card. He posted a video online shortly after the incident, in which he accuses Werdum of punching him in the face. He also uses an anti-gay slur in Werdum's direction.
The New South Wales police department released a public statement on Thursday, stating a 40-year-old man had been charged with common assault after striking a 29-year-old man in the neck with a boomerang. Neither man was treated for injuries. The New South Wales police did not identify either man.
Werdum's manager Ali Abdelaziz told ESPN he could not confirm the assault charge, but denied Werdum threw a punch.
"The plastic bag landed on his shoulder, and there was a boomerang in it," Abdelaziz said. "He kicked Fabricio first. He said he got punched in the face, where is the video of that?
"The kind just wants to make a name for himself. I think some of the stuff he is saying is borderline racist. But Fabricio is 250 pounds. If he had punched Colby in the face, he'd be knocked out or in a hospital."
Videos of the altercation surfaced late Wednesday. A video posted by UFC welterweight Dan Hooker clearly showed Werdum throw a bag at Covington, but it did not show a punch.
The UFC released a brief statement on the incident on Wednesday, saying it was "aware of the altercation between Fabricio Werdum and Colby Covington" and intended to "conduct a full investigation."
Covington (13-1) was at the source of some controversy last month, when he called Sao Paulo, Brazil a "dump" before facing Demian Maia at an event there. After defeating Maia via decision, Covington referred to the Brazilian crowd as "dirty animals."
The UFC could discipline Covington for his use of an anti-gay slur. Just two months ago, the UFC stated Werdum had agreed to perform community outreach within the LGBTQ community in Las Vegas for offensive language during a media event. According to Abdelaziz, Werdum has not completed that outreach program but plans to do so.