Phelps and King weigh in on 'drug cheat' debate

Cape Town - Michael Phelps and fellow swimming gold medalist Lilly King have added their voices to Mack Horton's call for convicted "drug cheats" to be excluded from the Olympics.

Australian 400m Freestyle gold medalist Horton incurred the ire of Chinese officials and fans labelling opponent and silver medalist Sun Yang as a "drug cheat".

The prevalence of banned substances has been a recurring theme at the Rio 2016 Olympics, with revelations of widespread use among Russian athletes grabbing headlines in the weeks leading up to the games.

Sun Yang, a gold medalist at London 2012 who has already won a gold and silver in Rio, was banned for three months in 2014 for testing positive for a banned substance. Horton was not shy to remind him of his offence, or to call his victory one "for the good guys".

The Chinese swimming team demanded an apology, calling the comments a "malicious personal attack", but Australia's chef de mission Kitty Chiller insisted that they "have no intention of making an apology" and that Horton "has every right to express his views and his displeasure".

Horton now has the support of the most successful Olympian of all time, American swimmer Michael Phelps, whose latest gold medal took his personal tally up to 23 medals.

"To have somebody test positive not just once but twice and still have the opportunity to swim at these Games, it breaks my heart," Phelps said. "I wish somebody would do something about it."

Another Olympian to have her say is 100m Breaststroke gold medalist Lilly King, who spoke out against Russian rival and two-time doping offender Yuliya Efimova as well as her own United States teammate Justin Gatlin.

32-year-old sprinter Gatlin, an Athens 2004 gold medalist who also bagged bronze at London 2012, incurred a four-year ban in 2006 for testing positive, his second offense after a similar ban in 2001, but has been cleared to compete in Rio.

"I have to respect [the Court of Arbitration's] decision even if it is something I don't agree with," the 19-year-old swimmer said.

"But do I think people who have been caught for doping should be on this team? No. It is unfortunate we have to see that."