The materials for the gold, silver and bronze medals awarded throughout the 2012 London Olympics will be provided by international mining company Rio Tinto.

4,700 medals will be won and Rio Tinto's sponsorship is worth about $15,500,000.

Rio Tinto has supplied the metals for Olympic gold, silver and bronze medals once before - at the 2002 Salt Lake City Games.

The company's chief executive Tom Albanese says the company is 'excited to have the special job once again of digging the ore that will become treasured medals for the world's elite athletes.'