Foot injury clouds Kim Yu-Na Sochi plans
Gold medalist Kim Yu-na of South Korea displays the South Korean national flag at the 2013 World Figure Skating Championships in London, Ontario, March 16, 2013
The Korea Skating Union (KSU) said Kim had suffered a metatarsal injury to her right foot.
"The injury requires at least six weeks of treatment and an unspecified period of rehabilitation afterwards," a KSU official told AFP.
The 23-year-old reigning Olympic champion will be forced to skip at least two International Skating Union (ISU) Grand Prix series -- one in Canada in October and the other in France in November.
She had trained hard for both events as part of her preparations for the 2014 Winter Olympics in Sochi in Russia in February.
The South Korean superstar made her competitive return to the ice in December last year after a break of more than 18 months from the sport.
In March she won her second world title in Canada, setting herself up as a strong contender for back-to-back Olympic gold medals.
Known as "Queen Yu-Na" in her native country, Kim won silver at the 2010 worlds, after which she took a lengthy break. She finished second at the event in 2011 before dropping out of competition again.
Kim has said that she would retire after the 2014 Winter Olympics and seek to become a member of the International Olympic Committee.