Michael “Superfish” Phelps has got some serious competition in the endorsement stakes: Park Tae-hwan, Olympic 400m free champion from South Korea, has become the focus of advertising campaigns valued at more than £51 million since winning the country's first Olympic gold in swimming, industry executives told local media.

Park, nicknamed "marine boy" back home, signed major endorsement deals ahead of the Games after he became the first Korean world swimming champion, in the 400m freestyle, last year in Melbourne. South Korea, host of the 1988 Olympic Games, has several sports heroes but Park has captured the imagination in a bigger way than any of them, it seems.

The 18-year-old, described by his home media as “charismatic”, got closer to Australian Ian Thorpe's 400m freestyle world record than any other man ever has on his way to gold at the Water Cube. He also took silver behind Phelps in the 200m freestyle.

Two major companies signed Park up as the face of their products before the Games, SK Telecom and Kookmin Bank. "The value of the impact from our advertising campaign with Park has increased by ten-fold," said Kim Jin-young, a Kookmin Bank spokesman. Both companies have already stepped up their campaigns with Park, who has saturated the South Korea airwaves since the Games started. In total the campaigns are valued at more than £51 million.

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Park will also receive in the order of £321,000 in prize money from his Government and various other sponsors, according to the Korean media. His country will now bid to host the post London 2012 world championships in 2013 and the new pools complex that would be built for the event would carry the name of the Olympic 400m champion.

Meanwhile, the maker of the oversized headphones Park wore on his way to his blocks in Beijing has enjoyed a run on its products. "After he put on our headphones in the Olympic Games, calls for purchases are skyrocketing," said Kim Young-rang from the manufacturer Cresyn.