China's top swimmer, Sun Yang, has been banned for eight years for breaking anti-doping rules, meaning the Olympic champion will miss Tokyo 2020 this summer.The decision effectively ends the 28-year-old's career.He reacted angrily, saying he "firmly" believed in his innocence and "facts must overcome lies".Sun is the reigning world and Olympic champion in the 200m freestyle.

He won two gold medals at the 2012 London Games and another at Rio de Janeiro in 2016.He was branded a drug cheat by rivals at Rio, and two competitors refused to stand with him on medal podiums at the world championships last year.The ruling by the Court of Arbitration for Sport (CAS) came after it earlier accepted an appeal from the World Anti-Doping Agency (WADA).WADA was unhappy about a decision by swimming body FINA to clear Sun of wrongdoing over his conduct during a test in 2018.Sun and members of his entourage were accused of smashed vials containing blood samples taken at an out-of-competition test in September of that year.A panel of three CAS judges agreed in a unanimous verdict that Sun had failed to establish a "compelling justification to destroy his sample collection containers and forego the doping control".Image:Sun Yang says he believes 'firmly' in his innocenceSun had alleged there was an error in collection protocol, but CAS said the "personnel in charge of the doping control complied with all applicable requirements".The organisation added that the lengthy, eight-year term was imposed because Sun had already served a three-month ban in 2014, when he tested positive for a stimulant outlawed at the time.He can appeal to Switzerland's supreme court, but on narrow procedural grounds, while his lawyers have already had three federal appeals dismissed on legal process issues.Sun said: "I have entrusted a lawyer to appeal to the Swiss Federal Supreme Court in accordance with the law.

I will let more people know the truth."I firmly believe in my innocence.

Believe that facts must overcome lies.

I will fight to the end to defend my legitimate rights and interests."