SEOUL (AFP) - South Korea's Olympic body said on Friday it would file a complaint with the international governing body for figure skating over controversial judging which saw Olympic defending champion Kim Yu Na relegated to silver at the Winter Games.

The Korean Olympic Committee (KOC) said it would send a joint letter with the Korea Skating Union (KSU) to the International Skating Union (ISU) calling for an investigation into the composition of judges for female singles competition in Sochi.

"The KOC and the ISU decided to file complaints with the ISU disciplinary committee," the KOC said in a statement.

The committee said it would ask the ISU's disciplinary committee to see if there was a violation of ethical rules by the judging panel.

Kim, 23, finished second in Sochi behind Russian skater Adelina Sotnikova, despite turning in a characteristically error-free performance.

Her unexpected defeat sparked fury in South Korea where she is known as "Queen Yu Na" and enjoys a passionate, devoted following among millions of people of all ages.

Kim has repeatedly said she has put the Olympics behind her.

But more than two million fans who believe she was robbed of a repeat Olympic gold medal have signed a petition calling for a review of the result.

Kim was seeking to become the first woman to win back-to-back Olympic titles in figure skating since the then East Germany's Katarina Witt in 1988.

Under growing pressure from fans, the KOC decided to take action, citing "unreasonable and unfair" judging.

"We've been very cautious because our appeal or complaint could hurt relations with the ISU and international judges for figure staking, or bring disadvantage to our players in international competition," an unnamed KSU official said in the statement.