Ryan Lochte Held Up at Gunpoint in Rio ... IOC Calls Story BS

10:10 AM PT -- Lochte says he was in a cab with three other swimmers when, according to a report, the driver was pulled over by men flashing badges and claiming to be police. The fake cops told everybody in the cab to get down on the ground, and three of the swimmers followed orders, but Lochte refused, saying he did nothing wrong. At that point, according to the report, one of the robbers put a gun to Lochte's head and cocked it, demanding his wallet. Lochte obliged.

9:30 AM PT -- A rep for Brazilian swimmer, Thiago Pereira, says he was with Lochte at Club France celebrating a friend's birthday before the incident.

Ryan Lochte was reportedly held up at gunpoint this weekend in Rio ... apparently at a party in the city, but an IOC spokesperson says it's not true.

Lochte's mom says her son called her right after the stickup and says it was "terrifying" ... according to a Fox Sports Australia reporter. The reporter says the thief or thieves made off with Ryan's wallet.

Ryan was invited to the party by Brazilian swimmer Thiago Pereira, along with 3 of Lochte's teammates.

Another report says a second U.S. swimmer was held up along with Ryan.

The IOC says the story is "absolutely not true," but the Fox Sports reporter insists Ryan's mom debriefed him on the incident.

Story developing