A Brazilian judge has ordered for the IMMEDIATE seizure of Ryan Lochte's passport -- claiming he may have lied about a robbery incident in Rio ... but the swimmer is already back in the U.S.
Brazilian authorities have issued a statement to TMZ Sports saying, "Judge Keyla Blanc De cnop, the Special Court of the Fan and Major Events, ordered the dispatch of search warrants and seizure of passports of American swimmers Ryan Lochte and James Feigen."
"With this, they are prohibited from leaving the country."
Lochte and Feigen had claimed they were together when their taxi cab was stopped and the swimmers were robbed by people posing as cops.
Brazilian authorities say they have found contradictions in the swimmers' stories -- and they want to speak with them both ASAP.
Officials say Lochte claimed they were only robbed by ONE person. Feigen said there were multiple culprits.
Officials also point to surveillance video that shows the swimmers in good spirits when they returned to the Olympic Village after the alleged incident -- not acting like people who were just robbed at gunpoint.
We spoke with Lochte's attorney, Jeff Ostrow, who tells us straight up -- "I have no information from Brazilian authorities that they want his passport."
"I’m shocked to hear that they would go to such measures in an effort to further investigate the incident as he has been nothing but cooperative with authorities, including sitting for a full interview with the Tourist Police, U.S. State Department, USOC Security, FBI, and anyone else that requested to be present."
He added, "Ryan is safely back in the United States."
No word on the whereabouts of Feigen.