Olympic swimmer Kenrick Monk has tearfully admitted to inventing a story about being the victim of a deliberate hit-and-run car incident.

In a blow to his chances of representing his country again, Monk, 23, revealed he had broken two bones in his elbow while skateboarding on Wednesday.

At the time he told media he had been riding his bicycle when a P-plate car had hit him and driven off.

But on Saturday, at the pool where he trains in Brisbane, he told a media conference he had made up the story out of embarrassment.

With coach Michael Bohl by his side, he admitted he had recently bought a skateboard and fallen off it on his way to training.

The sprinter, who won a gold medal with the 4x200 metres relay team at the 2010 Commonwealth Games, broke down as he revealed to reporters he had told his parents and the police the truth that morning.

"I didn't know what to do ... I panicked, I freaked ... basically to know that I've just fallen off a skateboard, something that a 10-year-old can ride," Monk said.

"It's preparation now, you're leading up to the Olympics. It's not the brightest thing to be on a skateboard."

He broke down as he said he had made up the accident tale because it sounded "elaborate".

"It just kept snowballing and snowballing and more and more and more came out and it just got too much for me," he said.

He said he had been prompted to change his story when police told him on Friday they had a witness to the incident who contradicted his own account.

He added that he would have eventually told the truth anyway.

"No, I would have come forward. I just can't handle it no more," he said.

"It's just been laying there and I feel sick."

Monk said he was worried about being thrown off the team but it was out of his hands.

"I'm trying not to think of that, (I'm) just trying to get over the day at the moment, trying to get through my operation," he said.

He faces up to six weeks out of the water and has been told he will lose 10 per cent reach in his dominant right arm.

Bohl said he was disappointed Monk had made up the story but the swimmer was under a lot of pressure with the Olympic trials coming up in March.

"It's different to telling a lie to your parents or family, there's no one really affected by that," he said.

"But when you're telling it to 23 or 24 million people it's a lot more serious, so I think Kenrick, I can tell you first-hand, is very very remorseful for what's happened."

Bohl said it was a matter for Swimming Australia to decide whether the lie would affect Monk's chances of Olympic selection in March, and said the swimmer would front a Swimming Australia (SA) disciplinary committee.

Former Australia Olympics team coach Laurie Lawrence, a friend of Bohl's, said he hoped Monk, if he qualified, could still make it to London next year.

"As long as he is not charged by police, he hasn't broken any laws," Lawrence said.

"He told a lie, and now he has admitted it."

Police are yet to comment on whether Monk might face any public nuisance charges over the lie.

Monk had described the incident to media in detail at the time.

"I remember the guys in the car yelling 'Oi' and laughing. I turned and I got whacked on the side - that was it," Monk said at the time.

"I thought it was a scare tactic but it went too far. They were young and dumb, trying to impress their mates."

SA chief executive Kevin Neil released a statement on Saturday, saying: "The entire matter is regrettable and we will be making no further comment until the full details of the incident are known."

AAP