London boasts of most expensive Olympic medals

The eight tons of gold, silver and copper unearthed from mines in Mongolia and Utah and now under guard at the Tower of London is the largest ever haul used to make Olympic medals.

"The medals arrived at the tower on July 2. We will keep them under tight security" Tracey Sands, spokeswoman for Historic Royal Palaces, told AFP.

The 4,700 Olympic and Paralympic medals will be guarded alongside Britain's crown jewels until they are presented on the podium.u00a0