US Olympic swimmer Ryan Lochte has confirmed he was robbed at gunpoint in Rio de Janeiro on Sunday morning.

The 32-year-old said he was with fellow US swimmers Gunnar Bentz, Jack Conger and Jimmy Feigen when their taxi was stopped by thieves posing as police.

"We got pulled over in the taxi and these guys came out with a badge, a police badge, no lights, no nothing, just a police badge, and they pulled us over," Lochte told the NBC's Today program.

"They pulled out their guns, they told the other swimmers to get down on the ground. I refused. I was like, we didn't do anything wrong so I'm not getting down on the ground.

"And then the guy pulled out his gun, he cocked it, put it to my forehead and he said, 'Get down,' and I put my hands up. I was like, 'whatever'. He took our money, he took my wallet. He left my cell phone, he left my credentials."

The athletes were returning to the Olympic village after celebrating the end of the swimming competition at the Rio Games.

A US Olympic Committee spokesperson said: "Their taxi was stopped by individuals posing as armed police officers who demanded the athletes' money and other personal belongings. All four athletes are safe and are cooperating with authorities."

Lochte's mother, Ileana, told the USA Today that she had spoken to her son on the phone. "I think they're all shaken up. There were a few of them," she said. "They just took their wallets and basically that was it."

Lochte, 32, has won six Olympic gold medals, including his victory with the USA's 4x200m freestyle relay team in Rio.