Doping in Swimming

US coach claims doping the "biggest threat" to swimming competition at Rio 2016

This follows the surfeit of doping-related controversies in the sport, including allegations this month that Russian anti-doping officials unsuccessfully requested money in return for covering up failed drug tests registered ahead of London 2012.

Particular concerns have been raised in relation to Russian and Chinese swimmers, with world champion Yuliya Efimova and Olympic gold medal winning counterpart Sun Yang among leading athletes to be implicated.