American swimmer Ryan Lochte fabricated a story about being robbed at gunpoint in Rio de Janeiro, according to a Brazilian police official.

The official told the Associated Press that at around 6am on Sunday, Lochte, along with fellow swimmers Jack Conger, Gunnar Bentz and Jimmy Feigen, stopped at a petrol station in Barra da Tijuca, a suburb of Rio where many Olympic venues are located.

One of the swimmers tried to open the door of an outside bathroom but it was locked, the official said.

A few of the swimmers then pushed on the door and broke it, the official said, and a security guard appeared and confronted them.

The official says the guard was armed with a pistol, but he never took it out or pointed it at the swimmers.

According to the official, the petrol station manager then arrived.

Using a customer to translate, the manager asked the swimmers to pay for the broken door, the official said.

After a discussion, they did pay him an unknown amount of money and then left, the official added.

The official said that Conger and Bentz, who were pulled off a plane going back to the US last night, told police that the robbery story had been fabricated.

The situation escalated last night when Conger and Bentz were pulled from a flight at Rio de Janeiro airport amid uncertainty over what truly took place

United States Olympic Committee (USOC) spokesman Patrick Sandusky said late on Thursday morning that Lochte's team-mates were scheduling a time and place to meet with authorities.

The situation escalated last night when Conger and Bentz were pulled from a flight at Rio de Janeiro airport amid uncertainty over what truly took place during the late-night outing after the Olympic swimming had ended at the Rio Games.

Court officials had called for the four swimmers' passports to be seized, but Lochte had already returned to the United States before authorities could enforce the decision.

Representatives from the US consulate arrived at the airport shortly after the swimmers were stopped from leaving the country on Wednesday night.

Brazilian authorities continued pressing the American swimmers over the ever-changing account of the robbery. Police said the swimmers were unable to provide key details in early interviews and they found little evidence to support the robbery claim. The swimmers said they had been intoxicated and could not remember what type and colour of taxi they were in, where the incident happened or what time the events occurred, police said. The police official said officers grew suspicious when they reviewed security video of the swimmers returning to the athletes' village and saw them wearing watches.

The office of Judge Keyla Blanc, who ordered the passports seized, said there were discrepancies in the statements by the swimmers.

Lochte had said he was with Conger, Bentz and Feigen when they were robbed at gunpoint in a taxi by men with a police badge as they returned to the athletes' village from a party several hours after the final Olympic swimming events on Saturday.

NBC reported on Wednesday night that Lochte backed off some of his earlier claims, saying the taxi was not pulled over by men with a badge but rather the athletes were robbed after stopping at a petrol station. Lochte also said the assailant pointed a gun at him rather than putting it to his head.

Authorities said that after the incident, the swimmers did not call police; officers began investigating after they saw media reports in which Lochte's mother spoke about the incident.

Lochte's lawyer, Jeff Ostrow, previously said there is no question the robbery occurred.

"Why would anybody fabricate anything?" Steve Lochte said. "It's just ridiculous."

Lochte told USA Today that he and his team-mates did not initially tell US Olympic officials about the robbery because "we were afraid we'd get in trouble".

The British Olympic team said on Thursday one of its athletes was also robbed in Rio. The British Olympic Association was responding to a Guardian report that the unnamed athlete was held up at gunpoint after a night out. The BOA declined to say if the incident was reported to police.

While he has won many medals in the Olympic pool, Lochte's accomplishments have long been overshadowed by team-mate Michael Phelps - the most decorated Olympian in history. Lochte won a gold in Rio in a relay race alongside Phelps.