Lochte, USOC say sorry

US gold medallist swimmer Ryan Lochte on Friday apologised for his behaviour at the Olympics after being accused by Brazilian police of inventing a story about an armed robbery to cover for some bad behaviour at a gas station.

"I should have been much more responsible in how I handled myself, and for that am sorry to my team mates," he said on Instagram.

Lochte, together with fellow US swimmers Gunnar Bentz, Jack Conger and Jimmy Feigen, are accused of having fabricated a story about being robbed by gunmen posing as policemen.

Surveillance footage and an investigation by Brazilian authorities showed that they had vandalised a gas station bathroom and had handed over money to armed security guards who had prevented them from leaving.

In his apology, Lochte, 32, described the night as "traumatic".

"It's traumatic to be out late with your friends in a foreign country -- with a language barrier -- and have a stranger point a gun at you and demand money to let you leave," he said.

"But regardless of the behaviour of anyone else that night, I should have been much more responsible in how I handled myself and for that am sorry to my team mates, my fans, my fellow competitors, my sponsors, and the hosts of this great event."

Lochte, Bentz and Conger have returned to the United States, while Feigen was still in Brazil on Friday morning. Feigen had agreed to pay $11,000 to a Brazilian charity, police said. His passport would be released upon providing a receipt.

Earlier, Rio's mayor, Eduardo Paes, accepted an apology given by the US Olympic Committee over the incident involving the swimmers, but he said he had "pity and contempt" for the athletes involved.

Paes said on Friday that the behaviour of four did not represent the good spirit that the rest of the American delegation had shown. He also emphasized that US tourists were always welcome in his city.