One of the most conspicuous is table tennis player Geng Lijuan, the former world number one from China who has for more than a decade represented Canada.

BBC: Defecting dilemmas for Games

Elsewhere on day 15 of the Games, China's world number one Zhang Yining won back-to-back table tennis golds, after defeating team-mate Wang Nan to hand the hosts a clean sweep of the medals in the women's singles.

CNN: France win BMX gold as Briton Reade crashes