More than 100 medals won at the Rio Olympics have been returned to organisers because they have rusted or developed black spots on them, the Games' spokesman said on Friday.
At least 130 medals, mostly bronze and including some from the Paralympics, are being fixed by the Brazilian Mint who made them for last year's event, Mario Andrada said.
"The most common issue is that they were dropped or mishandled and the varnish has come off and they've rusted or gone black in the spot where they were damaged," Andrada said.
"The second thing is that a small few, about 10, had problems with the extreme cold."
Andrada said the first problems came to light in October but called them "completely normal".
A total of 2488 medals were produced for the Olympics and hundreds more for the Paralympics. The silver and bronze medals were produced using 30 per cent recycled materials.