Team GB member robbed at Rio 2016
United States swimming star Ryan Lochte had a gun held to his head this week as he travelled in a taxi, before having his wallet stolen.
The British Olympic Association has confirmed that a member of their delegation has also been robbed, although they are "accounted for, and are safe and well".
A BOA spokesman said: "We can confirm there has been an incident of theft involving a Team GB athlete returning to their accommodation.
"All members of our delegation, including the individual concerned, are accounted for, and are safe and well."
Athlete safety was a key topic in the build-up to the Games. Australian Olympic Committee (AOC) chef de mission Kitty Chiller said in June that "no-go zones" and curfews may be forced upon their competitors in a city hit by police strikes, with officials warning "Rio de Janeiro will not be safe".
Australian athletes were subsequently banned from visiting beaches after dark in the Brazilian city.
A report in the Guardian claims that the BOA have called a post-Games security briefing with all athletes, who have been told to avoid leaving the Olympic village and instructed not to wear official uniform.