The drama happened hours after a judge ordered gold medallist Ryan Lochte and team-mate Jimmy Feigen to stay in the country as police investigate their claim they were robbed during the Olympics.

USOC spokesman Patrick Sandusky confirmed the swimmers were detained but had no other details.

Lochte and his three team-mates said they were held up at gunpoint in a taxi as they returned to the athletes' village from a party, several hours after the last Olympic swimming events were held.

Police have found little evidence so far to support their accounts, and say the swimmers were unable to provide key details in interviews.

The office of Judge Keyla Blank gave the order earlier on Wednesday to seize the passports of only Lochte and Feigen.

Lochte's father, Steve Lochte, told The Associated Press by phone from his Florida home that his son called him on Tuesday after arriving in the US.

The 32-year-old swimmer was going to pick up his car and buy a new wallet to replace the one that he said was stolen in the robbery.

"I'm just happy he's safe," the elder Lochte said. "It was an unfortunate experience for him and the other three. I don't know what all the controversy is. They were basically taken out of the taxi and robbed. The main thing is he's very lucky that he's safe and that all they got was his cash and wallet."

He said his son's Olympic credentials and mobile phone were not taken during the incident early on Sunday morning. He said he was sure Ryan had his passport or he would not have been allowed to board a plane.

Associated Press reporters waiting outside Lochte's home in North Carolina did not see the 12-time medallist.

Feigen's whereabouts could not immediately be confirmed, though he told the San Antonio Express-News he was still in Brazil.