US swimmers Gunnar Bentz and Jack Conger stopped at Rio airport
US Olympic swimmers Gunnar Bentz and Jack Conger have been stopped from leaving Brazil by police examining claims they were robbed in Rio.
The two men were taken off a US-bound plane at Rio de Janeiro airport, and taken in for police questioning.
Teammates Ryan Lochte and James Feigen were also told not to leave Brazil while police clear up what they say are inconsistencies in the men's story.
Mr Lochte, however, had already returned to the US on Monday.
He admitted on Wednesday to some inaccuracies in his original account of being robbed at gunpoint in the early hours of Sunday, but vehemently denied making the story up.
"I wouldn't make up a story like this nor would the others - as a matter of fact we all feel it makes us look bad," he told US TV network NBC.
The three swimmers remaining in Brazil - who have been ordered by a judge to surrender their passports - are expected to speak to investigators on Thursday.
Mr Lochte is one of the most successful swimmers in history, with 12 Olympic medals, and he once had his own reality television show in the US. In Rio, he swam in two events, winning gold in the 4x200m freestyle relay.
Mr Feigen won gold in the 4x100m freestyle relay.
Mr Bentz competed in the 4x200m preliminaries, but not the final. He still received a gold medal after the US team's win.
What has been the reaction to the arrests?
US Olympic Committee (USOC) spokesman Patrick Sandusky said in a statement: "The three US Olympic swimmers [Gunnar Bentz, Jack Conger and James Feigen] are co-operating with authorities and in the process of scheduling a time and place today [Thursday] to provide further statements to the Brazilian authorities.
"All are represented by counsel and being appropriately supported by the USOC and the US consulate in Rio."
Earlier he said that Mr Bentz and Mr Conger had been "released by local authorities with the understanding that they would continue their discussions about the incident on Thursday... James Feigen is also communicating with local authorities and intends to make further statements regarding the incident on Thursday as well."
Mr Lochte's lawyer told the BBC he had returned to the US two days ago before the controversy broke.
"He was never asked to remain for further investigation or for any other purpose after he met with Brazilian authorities after he gave a statement," said Jeffrey Ostrow.
- The Video: Surveillance footage taken as the team returned to Olympic village appears to show the swimmers passing valuables through a metal detector, despite telling police that items had been stolen.
- The Robbers: Mr Feigen said several men had robbed the group but Mr Lochte told Brazilian authorities one man had targeted the group
- The Gun: Mr Lochte initially told US media that the robber had placed a cocked pistol against his forehead but in a later interview said that gun had only been pointed in his general vicinity.
- The Encounter: Mr Lochte first claimed that their taxi was pulled over but later said that the car was already stopped at a petrol station when the robber approached
Read more: Plot thickens at Rio Olympics
What do we know of the alleged robbery?
Accounts of what happened to the swimmers have been confusing from the beginning, and it appears they did not immediately alert either the Brazilian police or the Olympic authorities about it.
News of the incident emerged after Mr Lochte's mother told US media about it.
Mr Lochte himself gave an initial account of the events to NBC on Sunday, saying he and the other swimmers had been in a taxi returning from a club in the early hours when they were pulled over by men wearing police badges.
He said they had pulled a gun and told the swimmers to get on the ground. "I refused... and then the guy pulled out his gun, he cocked it, put it to my forehead..."
Mr Lochte has since slightly altered his account, telling NBC on Wednesday that the taxi had not been asked to pull over - they had been robbed while making a stop at a petrol station - and he said the gun had not been pointed directly at his forehead.
He called the inconsistencies a "traumatic mischaracterisation" caused by the stress of the incident.
What has been the Brazilian authorities' reaction?
The judge investigating the case found further inconsistencies and ordered police on Wednesday to seize the swimmers' passports to prevent them leaving Brazil.
These inconsistencies reportedly include the time the swimmers left the party, and how many alleged gunmen they were confronted by.
Police say they have not been able to track down the driver who the swimmers say drove them back to the village.
And CCTV footage of their return to the athletes' village appears to show the swimmers laughing and joking, and handing over their wallets, phones and accreditation, as they go through the security screens. The judge said they had not show signs of being affected by a robbery.
Meanwhile, in an unrelated development, Australian swimmers Josh Palmer and Emma McKeon have been disciplined after they failed to return to the Olympic Village on Tuesday night following a night out in Rio with teammates.
The pair have been ordered to remain in the village between 20:00 and 08:00 and only travel to events in official transport. They have also been banned from participating in the closing ceremony.
Ms McKeon chose to stay the night with swimming friends in the Copa district without informing team management, while Mr Palmer was found in a disoriented state after apparently being robbed.