Ryan Lochte

The decorated U.S. swimmer posted a statement on social media Friday, apologizing for his actions over the weekend in Rio that landed him and three other swimmers in a whirlwind of Olympic controversy.

Lochte's teammates Gunnar Bentz and Jack Conger landed in Miami on Friday after testifying about the alleged robbery described to police. The lawyer for the fourth U.S. swimmer, James Feigen, said he would make a $10,800 "donation" and leave Brazil later in the day.

The Brazilian authorities stopped Gunnar Bentz and Jack Conger from boarding the flight at Rio de Janeiro airport, bound for the US, for questioning late on Wednesday.

Two teammates - Ryan Lochte and James Feigen - were barred from leaving the country, but Lochte had already left.

Police have queried their accounts of a robbery they reported in Rio on Sunday.

The four swimmers said they had been robbed at gunpoint in a taxi in Rio.

But police said their account of when they arrived at the Olympic Village did not square with CCTV recordings.

Lochte, Gunnar Bentz, Jack Conger and Jimmy Feigen were stopped by people posing as armed police, the US Olympic Committee (USOC) said in a statement.

The robbers demanded money and other personal belongings.

After reports emerged of the incident, the USOC initially denied that Lochte had been robbed.

"All four athletes are safe and co-operating with authorities," the USOC's statement said.

The group had been attending a party at the French Olympic team's hospitality house when their taxi was stopped on the way back to the athletes' village.