Chen Zhiyu, head of the Beijing anti-doping division, said the samples could be reexamined as more advanced testing techniques are developed, the China Daily said.
Previously, samples that tested positive were stored for 90 days and those that tested negative for 30 days, according to the anti-doping rules of the International Olympic Committee (IOC).
The 29th Olympic Games in Beijing are due to see a record 4,500 doping tests, some 25 % more than at the 2004 Athens Olympics, and 50% more than in Sydney in 2000.
China opened the world's biggest and most advanced anti-doping laboratory specifically for the 2008 Beijing Olympics. Chinese authorities spent $10 million on the new laboratory, including $2.7 million on state-of-the-art testing equipment. The lab employs 100 experts from 10 countries.
Seven Russian female athletes, including five selected for the Beijing Olympics, were recently suspended for providing false urine samples and "tampering" with doping control procedures.
