His arm raised in a Nazi-style salute, a Lithuanian fan goads two black Olympic stewards.
The gesture, caught on camera by an English couple at a basketball game, was also witnessed by two policemen, but they appeared to do nothing about it.
While the police insist they are investigating the incident at the Basketball Arena in the Olympic Park, anti-racism groups say officers should have removed the man.
He was part of a rowdy group of Lithuanians who stood chanting during their country's game against Argentina.
As two black stewards approached to ask them to sit down, one responded with what appears to have been a Nazi salute, despite the policemen nearby.
A witness said: "I was waiting to see if the officers would do anything, but they didn't seem to move".
"We can't let things like this go," said Ged Grebby, of campaign group Show Racism the Red Card.
- Daily Mail