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 United States late on Wednesday, told police that the robbery story had been fabricated.

Lochte and the three other American swimmers should be given "a break", Rio 2016 spokesman Mario Andrada said on Thursday.

Rio 2016 spokesman Andrada apologised earlier in the week for the incident, but has no intention of retracting it once the facts of the story have been determined by the authorities.

"I do not regret having apologised...and no apologies from him and other athletes are needed," Andrada said at Thursday morning's daily media briefing.

"We need to understand that these kids were trying to have fun.

"They came here, they represented their country to the best of their ability. They trained for four years, they competed under gigantic pressure.

"I understand this issue is under investigation. I cannot go much further into the case.

"But let's give those kids a break. Sometimes you take actions that you later regret.

"Why should the swimmers apologise? No. They had fun, they made a mistake, it's part of life, life goes on."