The Melbourne Rebels are waiting for Amanaki Mafi and Lopeti Timani to return to Australia before they determine what, if any, punishment will be handed down over an alleged assault in Dunedin.

Mafi appeared in a Dunedin court on Monday morning on assault charges after an 'altercation' between he and his Rebels teammate in the early hours of Sunday morning.

He was released on bail, with a condition of non-association with Timani and his matter was adjourned until August 3.

The Rebels are currently beginning an internal investigation into the incident but the franchise plans to speak to both players separately when they return to Australia later this week.

Mafi is understood to be with team manager Tony Thorpe, while Timani is being looked after by the club doctor, who will accompany him on the flight back to Melbourne.

Timani, who debuted for Australia in 2016, had played his last game for the Rebels and will move to France in the coming months to play for La Rochelle.

Mafi has been an outstanding player for the Rebels in his two seasons at the club, and was last year voted as the Australian Super Rugby player of the year.

Though both players are coming off contract at the end of next month, it is believed Mafi and the Rebels were in discussions about a possible extension to his time at the club.

Whether this incident will affect those talks is yet to be seen, but the situation leaves Mafi's future in a somewhat perilous state.

The Japan international is set to play in the Japanese Top League in the Australian summer.

Rugby Australia and the Melbourne Rebels confirmed Mafi was in police custody on Sunday night after the 'altercation' between the pair.

The Rebels played the Highlanders on Saturday evening but their loss, combined with a victory by the Sharks in Durban later in the morning, saw the Melbourne club miss out on a finals spot.

It is understood Dunedin Police detained Mafi on Sunday morning, prior to the Rebels flying out.

Timani reportedly received "moderate injuries" but did not require hospitalisation.

Rugby AU and the Rebels issued a joint statement on Sunday night saying they were aware of the incident and that no other players were involved.

Though both said they would not comment until after the police matter was finished, Rebels chief executive Baden Stephenson expressed his anger in a brief statement, saying: “I am bitterly disappointed that an incident has occurred at the end of a season where we have taken pride in our on and off-field behaviour.

“We will respect the process and won't be making further comments until all investigations have taken place.”

It's not the first time Mafi has been involved in a club controversy, with the backrower ending his contract with Bath in 2016 after a reported dispute with the club doctor.