US swimmer Ryan Lochte said he overexaggerated what happened at a Rio gas station, admitting that his "immature behavior" got him and three teammates into trouble in the final days of the Olympics.

Lochte continued to backtrack from a story that he initially described as an armed robbery.

Police said the swimmers vandalized a bathroom after a night of partying and that armed guards confronted them and asked them to pay for the damage.

"It's how you want to make it look like," Lochte said in a portion of an interview with NBC's Matt Lauer that aired on Saturday.

"Whether you call it a robbery or whether you call it extortion or us just paying for the damages, we don't know. All we know is that there was a gun pointed in our direction and we were demanded to give money."

But he said he understood that he was being told that the US swimmers had to pay for the damage or the police would be called.

At this point in the interview, Lauer said: "You're striking a deal. Is that fair?"

Lochte replied: "We just wanted to get out of there," adding that the swimmers were frightened.

Lauer told Lochte that his story had morphed from being one about "the mean streets or Rio" to a negotiated settlement to cover up dumb behavior.

Lochte said: "That's why I'm taking full responsibility for it, because I over-exaggerated the story. "If I had never done that, we wouldn't be in this mess."

Lochte also said that he had lied in telling NBC interviewer Billy Bush the next day that a gun had been cocked and pointed at his forehead. He said that he was still under the influence of alcohol when he talked to Bush.

"I definitely had too much to drink that night and I was very intoxicated," he said.

As Brazilian police investigated his robbery claim, and eventually held his teammates for questioning while they sorted out his story, he had tweeted that he intended to dye it back.