The age of a third Chinese gymnast is in doubt, making half of China's women's gymnastics team possibly too young to compete in the Olympics.

Yang Yilin was born Aug. 26, 1993, according to 2004, 2005 and 2006 registration lists previously posted on the General Administration of Sport of China's website.

Yang is a medal favourite in the all-around and uneven bars, but the previously listed birth date would make her 15 at the end of August, below the minimum age of 16.

Yang's birth date on the 2007 registration list, however, is stated as Aug. 26, 1992, making her eligible.

The ages of two other Chinese gymnasts are also in doubt: He Kexin, a gold-medal favourite on uneven bars, and Jiang Yuyuan.

International Gymnastics Federation secretary general Andrei Gueisbuhler said he was unable to comment on Yang's case without seeing written records.

"If I don't have written proof of something ... we have to take for granted the passports that we've seen and have been checked by the IOC are OK," Gueisbuhler said.

Officials with the Chinese Gymnastics Association say that they have applied for passports for all of the athletes, and that photocopies of He and Jiang's passports, issued in July 2007 and March 2006, indicate they are both over 16.

"The International Gymnastics Federation strictly verified their passports and confirmed that their ages met the age rules for participating in the world championship, World Cup and Olympics," the association said in a statement.

The International Olympic Committee was in contact with the federation and Chinese officials regarding the age issue, IOC president Jacques Rogge said Saturday.

"The IOC relies on the international federations, who are exclusively responsible for the eligibility of athletes," Rogge said. "It's not the task of the IOC to check every one of the 10,000 athletes."

The all-around gold medal is expected to be a competition between two countries: the United States and China. Yang and He were expected to be big contributors for the Chinese, both having scored 17s on the uneven bars this season.

The only member of the American team to score a 17 is Nastia Liukin.

In the gymnastics team finals, three team members compete in each event and all three scores count towards the total.