South Korea's Shin reacts after being defeated by Germany's Heidemann during their women's epee individual semifinal fencing competition at the ExCel venue at the London 2012 Olympic GamesReuters 
North Korea's captain Kim Chung-Sim, Kim Song-Hui and Ri Ye-Gyong walk out into the arena ahead of their women's Group G football match against Colombia at the London 2012 Olympic Games in Hampden Park, Glasgow, ScotlandReuters 
South Korea's Yun Suk-young fights for the ball with Switzerland's Michel Morganella during their men's Group B football match in the London 2012 Olympic Games at the City of Coventry stadiumReuters 
Paraskevi Papachristou of Greece competes in the women's triple during the London Grand prix.Reuters 
Combination photo shows officials speaking to players from China and South Korea, and players from South Korea and Indonesia during their women's doubles group stage badminton matches during the London 2012 Olympic GamesReuters 
India's Vikas fights declared winner against Spence of the U.S. in their Men's Welter (69kg) Round of 16 boxing match during the London 2012 Olympic GamesReuters 
Ye Shiwen: This 16-year-old from China surprised many at the London Olympics 2012 by setting records besides beating the big names in the swimming world. She broke the world record held by Stephanie Rice in the women's 400m Individual Medley by clocking 4:28.43. She also created Olympic record in 200 metres individual medley event.Reuters 
File photo of South Korea's Wang Ki-Chun fighting with Nicholas Delpopolo of U.S. during men's -73kg quarter-final judo match at London 2012 Olympic GamesReuters 
Britain's Philip Hindes sits on the ground as he waits for assistance after falling during their track cycling men's team sprint qualifying heats at the Velodrome during the London 2012 Olympic GamesReuters 
File photo of Belarus' Nadzeya Ostapchuk holding her gold medal in the women's shot put victory ceremony during the London 2012 Olympic GamesReuters
The just concluded London Olympics 2012 was no doubt a big success with over 20 world records being broken in various disciplines but it has its own share of controversies. Some won medals but some were left in tears. As the games came to an end, we bring you the top controversies that threatened to marr the Olympics.
1) Clock Error
Korean fencer Shin A-Lam alleged that she was robbed off an Olympic medal in the women's epee. She was left in tears after a clock error cost her chance of winning a medal. She was through to the final when the clock hit zero but her opponent Britta Heidemann of Germany scored after Austrian referee Barbara Csar ruled that there was a second left. International Fencing Federation later announced 'a special medal' for the Korean fencer but she refused to accept the result.
2) Flag Error
The opening group match between North Korea and Colombia was delayed by over an hour after the Olympic officials displayed South Korean flag on the screen instead of North Korea flag.
3) Twitter Effect
Swiss footballer Michel Morganella was expelled from the Olympics after posting a racist tweet targetting South Koreans after his team's 2-1 defeat. He referred to the Koreans as a "bunch of mongoloids." The Swiss defender apologized to the Korean team for the racist tweet.
4) Racist Tweet
Greek triple jumper Paraskevi Papachristou was sent home after her racist tweet, triggering uproar at home. "With so many Africans in Greece... the West Nile mosquitoes will at least eat homemade food!!!" she posted on her Twitter page.
5) Badminton Scandal
The Badminton World Federation (BWF) disqualified eight badminton players from the women's doubles event at the London Olympics after being accused of "throwing away matches" for favourable draw in the knockout rounds. Two teams from South Korea and one each from China and Indonesia were disqualified for intentionally playing bad shots to throw away matches, which was not in the spirit of the Games.
[CONTROVERSIES AT LONDON OLYMPICS 2012 IN PICTURES]
6) Boxing Woes
Vikas Krishan's joy was short-lived as the International Boxing Association (AIBA) overturned the result of his pre-quarterfinal bout, just five hours after he had won against America's Errol Spence. The 20-year-old Indian had won 13-11 over Errol Spence of United States in a thrilling contest but in a dramatic turn of events, the AIBA declared the result 15-13 in favour of the American after the review of the match following an appeal from the U.S. team. They cited fouls committed by the Indian for the result overturn.
7) Swimming Too Fast
Ye Shiwen of China broke the world record held by Stephanie Rice in the women's 400m Individual Medley by clocking 4:28.43 at the London Olympics. Unfortunately, speculations were doing the rounds if she was doping. However, the Olympic officials have said that she is cleared the tests.
8) Doping
American judo fighter Nicholas Delpopolo was expelled from the Olympics after testing positive for marijuana. He admitted that he accidentally ate food baked with the banned sunstance.
9) Intentional Fall
Controversy broke out after British cyclist Philip Hindes told reporters after winning the team event that he deliberately crashed his bike for a better start. He however backtracked his earlier statement by saying that he fell after losing control of his bike.
10) Doping
Nadezhda Ostapchuk of Belarus was stripped of the women's Olympic shot put gold after testing positive for a banned substance. The International Olympic Committee (IOC) announced that it has disqualified and withdrawn the medal from her.
