For millions of South Koreans who stayed up into the early hours of Friday morning to watch their idol Kim Yu-na try to defend her Olympic figure-skating title, there was heartbreak and anger over her eventual silver finish.

Within hours of the result, the website of the popular online campaigning forum, Change.org, crashed as hundreds of thousands logged on to sign a petition calling for a review of the judges' scores.

The biggest name in South Korean sports, Kim has a fanatical following in her home country, and there was huge expectation that she would secure back-to-back golds going into Thursday's long programme in Sochi with a narrow lead over her rivals.

Her performance seemed flawless, but Russia's Adelina Sotnikova scored higher technical marks to take first place on the medal podium.

Kim skated last, shortly before 4:00am Korean time, and Korean TV commentators voiced surprise, verging on shock at the final result, with suggestions that the judges may have been swayed by the partisan Russian crowd.

"It will be interesting to see whether Sotnikova can ever obtain such a high score again down the road," said former skater -- and a former Kim Yu-Na coach -- Byeon Seong-Jin, commentating on the KBS channel.

"Today, Yu-na did not lose but Russia won," Byeon said.

A petition to challenge the result was set up immediately at Change.org and the website was swamped within hours.

"The petition gained 700,000-plus signatures in just six hours and is sending traffic to our site at five times the highest previously-recorded rate," Change.org spokeswoman Charlotte Hill told AFP.

"Approximately 90 percent of the traffic is coming from South Korea," Hill said, adding that the San Francisco-based company had a "team of engineers"  working to keep the server up and running. 

The final came too late for Korean newspapers' Friday print editions, but their websites were flooded with angry comments by ordinary South Koreans who felt that "Queen Yu-na" as Kim is known, had been robbed of the title.

"Kim Yu-na sheds tears at Russian bullying," ran a headline on the online edition of the JoongAng Ilbo newspaper.

"It was an unfair result ... Home advantage was to be expected, but we did not expect it to be displayed in such a way," the daily said.

An editorial by South Korea's Yonhap news agency noted that "many foreign media" had questioned the judges' decision.

"It is regrettable that the Olympics which must put the highest priority on fairness was marred by such a controversial judgement," it said.

The Sports Chosun website ran a balanced report of the competition, but the hundreds of comments it attracted were far from neutral.

"Congratulations Russia! You've become the most rotten Olympics in history.

Must be proud of that," wrote one disenchanted Kim fan.

"Sochi is just a shorter term for pick-pocket," wrote another.

Korean Twitter users voiced similar sentiments, although many also sent words of consolation to Kim and thanked her for everything she had achieved for her country.

"I made my conclusion" tweeted @Kjsultra in Korean. "Sotnikova's gold medal is given by Russia and Yuna Kim's medal is given by the rest of the world."

South Korean President Park Geun-Hye sent a personal message to Kim, who confirmed Friday that she was retiring from competition as she had said she would.

"Your beautiful performance at the Games will be remembered forever -- not only in the mind of Koreans but the whole world," Park said in her message, which made no comment on the judges' decision. (AFP)