Mixed martial arts star Conor McGregor hinted he may not be retiring after all on Wednesday after a racially-charged exchange of insults with rival Khabib Nurmagomedov.

In a cryptic post on Twitter which came a week after he had vowed to hang up his gloves, the trash-talking Irishman indicated he was not done with fighting.

"I want to move forward, with my fans of all faiths and all backgrounds," McGregor wrote. "All faiths challenge us to be our best selves. It is one world and one for all. Now see you in the Octagon."

McGregor's tweet appeared to be a response to criticism directed towards him after an earlier post in which he insulted Nurmagomedov's wife and the couple's Muslim faith. McGregor swiftly deleted the post made late on Tuesday.

Nurmagomedov however reacted furiously to the insult, raising reported sexual assault allegations which McGregor faces in Ireland according to the New York Times.

"You are a hypocrite who is not responsible for your actions," Nurmagomedov wrote. "Justice will find you. We will see."

The vitriolic exchange prompted an intervention from UFC chief Dana White, who urged both camps to dial back their rhetoric.

"I am aware of the recent social media exchange between Khabib Nurmagomedov and Conor McGregor," White said in a statement.

"The ongoing situation has escalated to a level that is unacceptable. As such, we are taking the necessary steps to reach out to both athlete camps and this situation is being addressed by all parties internally."

Nurmagomedov defeated McGregor in a bout last October in Las Vegas in a contest that was marred by a massive brawl at ringside.

In January, the Nevada State Athletic Commission handed McGregor a six-month suspension for his role in the post-fight melee, backdated to October.