The thousands of athletes striving to compete at London 2012 now know what treasure awaits at the end of their long and tortuous journeys after the medals for next year's Olympics were revealed in Trafalgar Square on Wednesday, one year before the start of the Games.

Measuring 85mm in diameter the gold, silver and bronze medals designed by British artist David Watkins are considerably larger than those in many previous Games and, weighing in at a hefty 400 grams -- the heaviest for a summer Games -- multiple champions may well be paying some excess baggage on their flights home.

As at all the modern Olympics since 1896, apart from Paris in 1900 when they were rectangular, London's medals are circular with one side featuring the obligatory Greek goddess Nike -- the symbol of victory and embodiment of the spirit of the Games.

It is the other side, however, that organisers say will encapsulate London's third hosting of the Games, following the previous editions in 1908 and 1948.

The now-familiar London 2012 logo features strongly in the abstract design, appearing to rise out boldly from the centre of the medal which is criss-crossed by lines which are meant to symbolise energy radiating out from the city.

"They could be particularly popular with javelin throwers," admitted Watkins. "Or fencers," he added, pointing to his design which also features the River Thames as a ribbon snaking through the heart of the medals.

Olympic triple jump champion Jonathan Edwards, who won his gold medal in Sydney in 2000 and who now works for London's organising committee, said the medals would be an inspiration to the world's sportsmen and women as the one-year countdown to the "greatest show on earth" begins in earnest.

"Athletes will look at the pictures today and say I want one of those," the world record holder told Reuters hours before the world got to see the design for the first time at a special one-year-to-go event in Trafalgar Square attended by IOC president Jacques Rogge.

"They will go out and train the next day with a little extra motivation, it's kind of a wake-up call, it crystallises what the challenges are."

Asked for his thoughts on the design, Edwards said the medals were "a chunky piece of kit".

"Compared to my Sydney medal it's a considerably bigger in diameter and also a lot heavier. It's beautiful and it's a chunky piece of kit. If you win seven or eight of them like Michael Phelps did in Beijing you'll need a strong neck."

While fame and fortune often await Olympic champions, Edwards said the medals themselves were the goal. "I slept with the medal under my pillow in Sydney," he said.

"It represents a lifetime's work."

Watkins, who was chosen from a shortlist of six to design the medals, said he was looking forward to the moment the first of the 2,100 medals were handed out.

"It is exciting to think that the finest athletes in the world will be wearing my design next summer,"

Watkins, who was involved making models for the cult movie 2001 - A Space Odyssey, said.

Gold medallists might be a little disappointed, however, to discover that their medals are actually 92.5 percent silver and contain just 1.34 percent gold, extracted from Rio Tinto's Kennecott Copper Mine near Salt Lake City.

The medals will go into production at the Royal Mint in South Wales later this year and will have the sport and discipline of the winning athletes engraved on the 7mm rim.