The International Olympic Committee expects cycling's governing body UCI to step up its doping fight following a report into the sport's doping culture revealed the UCI colluded with and protected Lance Armstrong.
Disgraced Boston and Chicago marathon champion Rita Jeptoo is maintaining her innocence over doping and has requested for a sample B test.
China's world and Olympic swimming champion Sun Yang served a three-month ban for a failed doping test earlier this year.
The head of the World Anti-Doping Agency (WADA) on Wednesday spoke highly of China's effforts in the fight against doping in sport, saying the country's anti-doping agency is one of the most "effective" organizations.
The International Olympics Committee will have the final say on whether Tyson Gay's 4x100m relay teammates will be stripped of their London Games medals in the wake of the sprinter's doping ban, the IAAF said.
Sprinter Tyson Gay accepted a one-year suspension on Friday after testing positive for a banned substance nearly a year ago and returned the silver medal he won in the men's 4x100m relay at the 2012 London Olympics.
Former world double sprint champion Tyson Gay has been suspended for one year after testing positive in 2013 for a banned anabolic steroid, the US Anti-Doping Agency (USADA) said on Friday.
Jamaican sprinter Asafa Powell, the former 100m world record holder, slammed the 18-month doping ban meted out to him on Thursday calling it "unfair" and "unjust".
Former world 100m record holder Asafa Powell received an 18-month doping ban on Thursday, two days after his fellow Jamaican sprinter Sherone Simpson got the same punishment.
Athens Olympics relay champion Sherone Simpson has been suspended for 18 months after testing positive for the banned stimulant oxilofrine during last June's Jamaican trials.
A Swedish Olympic official says hockey player Nicklas Backstrom has failed a doping test at the Sochi Games.
Disgraced former Tour de France winner Lance Armstrong has said he will testify with "100 percent transparency and honesty" at any independent enquiry into doping in cycling but wants assurances he will be treated fairly.