The World Anti-Doping Agency (WADA) has appealed to the Court of Arbitration for Sport against an independent tribunal's decision in August to clear tennis world number one Jannik Sinner of wrongdoing after he failed drug tests.

WADA said on Saturday the tribunal's finding of "no fault or negligence" on the Italian's part was incorrect under the applicable rules, and it would seek "a period of ineligibility of between one and two years" for the Australian Open and US Open champion.

The tribunal, organised by the International Tennis Integrity Agency (ITIA), had accepted Sinner's explanation that the anabolic agent clostebol entered his system from a member of his support team through massages and sports therapy.

Sinner, who beat Roman Safiullin on Saturday to reach the quarter-finals of the China Open, said he was surprised by WADA's decision.

"We cannot control everything, no? Obviously, I'm very disappointed and also surprised of this appeal, to be honest, because we had three hearings. All three hearings came out very positively for me," he told reporters in Beijing.

"We always talk about the same thing. Maybe they just want to make sure that everything is in the right position. Yeah, I'm just surprised that they appealed."

The ITIA said in a statement on Saturday: "The process was run according to World Anti-Doping Code guidelines; however, the ITIA acknowledges and respects WADA's right to appeal the independent tribunal's decision."

Sinner said his physio, Giacomo Naldi, applied an over-the-counter spray containing clostebol to his skin to treat a small finger wound and then administered massages between March 5 and 13 without using gloves, according to the ITIA.