In short:
Australian coach Michael Palfrey told South Korean media he hopes Kim Woo-min will win the men's 400 metres freestyle ahead of two Australian swimmers.
Palfrey has been involved in the coaching of Kim, who is the world champion in the event.
What's next?
Swimming Australia will decide if it takes any disciplinary action.
An Australian Olympic swim coach could be sent home from the Paris Games for publicly stating he hopes a star South Korean athlete defeats Sam Short and Elijah Winnington.
The Sydney Morning Herald reported Michael Palfrey told South Korean media in Paris he hoped world champion Kim Woo-min would win the men's 400 metres freestyle ahead of Australian duo Short and Winnington.
According to The Sydney Morning Herald, Palfrey was wearing Australian team colours and said "Go Korea" at the conclusion of the interview.
ABC Sport will be live blogging every day of the Paris Olympics from July 27
He has mentored South Korean swimmers in Brisbane, including Kim.
Palfrey, one of eight coaches on the Australian squad, has told team officials he was "very sorry" for his comments.
Swimming Australia head coach Rohan Taylor described the comments as "un-Australian" and he was considering expelling Palfrey from the Olympics.
"I am extremely disappointed," Taylor told reporters in Paris on Thursday.
"For a coach on our team to promote another athlete ahead of our athletes is not acceptable."
Taylor wants to decide Palfrey's tenure at the Paris Games as soon as possible.
Competition at the pool starts on Saturday.
"He either goes home or he stays, that's the options," Taylor said.
"And it's what is the impact on performance of the team.
"If he goes home, we have to find other coaches to pick up the load on the athletes and our coaches are really stretched, and is that in the athletes' best interest?
"That's one consideration.
"If he stays, then it's about the team dynamic and making sure that the [other] coaches are happy with that and can support that and the athletes themselves can go about their business and not be distracted.
"He made an error and I told him that I don't appreciate it … it was an un-Australian comment.
"Does that mean that he's unworthy of looking after the three athletes he has coached for the last three years to this point, who rely on him to prepare them for the performance?
"That is what I've got to weigh up."
Taylor said Australian coaches were given "guidelines" in March to end any association with non-Australian swimmers before the Paris Olympics.
Australia's Olympic chef de mission Anna Meares said Palfrey's comments were "a conflict and a serious error of judgement".
"He is very aware and very sorry for what has occurred," she said.
Meares said she would back any decision Taylor made.
"We won't be stepping in over the top of Swimming Australia," shesaid.
"We will be working with them and any decision that they make, we will support."
Meares said Palfrey's comments and whether he was still involved with Korean swimmers were both problematic issues.
"They both carry similar weight," she said.
Loading..."But the fact that he's commented about the athlete winning against the Australian team, that's the bigger issue."
Palfrey works with Australian swimmers Zac Incerti, Abbey Connor and Alex Perkins.
Kim won the men's 400m freestyle at February's world championships in Qatar, with Winnington finishing second.
Short claimed gold at the 2023 world titles in Fukuoka, with Kim and Winnington placing fifth and seventh respectively.
The men's 400m freestyle final will be held Sunday morning, Australian time.
AAP/ABC