World number one Jannik Sinner has been absolved of fault or negligence for two anti-doping failures in March.

Just weeks after winning his maiden grand-slam title at the Australian Open in January, the Italian twice tested positive for the banned substance clostebol, an anabolic agent that can aid muscle growth.

But the International Tennis Integrity Agency (ITIA) accepted Sinner’s explanation that the substance had accidentally entered his system via a product one of his team had used to treat a small wound.

Karen Moorhouse, ITIA CEO, said: “We take any positive test extremely seriously and will always apply the rigorous processes set out by WADA (the World Anti-Doping Agency).

“The ITIA carried out a thorough investigation into the circumstances leading to the positive tests with which Mr Sinner and his representatives fully co-operated.  

“Following that investigation, the ITIA accepted the player’s explanation as to the source of the clostebol and that the presence of the substance was not intentional. This was also accepted by the tribunal.”

Sinner, who warmed up for the US Open starting later this month by winning the Cincinnati title on Monday, first tested positive on March 10 while competing in Indian Wells.

He was red-flagged again in an out-of-competition test eight days later, with both samples yielding trace amounts of clostebol, but he was able to continue playing on the ATP Tour after successfully challenging a provisional suspension.

Scientific experts consulted by the ITIA concluded Sinner’s account – in which his physiotherapist had used an over-the-counter spray containing clostebol on his skin between March 5 to 13 – was credible.

Sinner said in a statement: “I will now put this challenging and deeply unfortunate period behind me.

“I will continue to do everything I can to ensure I comply with the ITIA’s anti-doping programme and I have a team around me that are meticulous in their own compliance.”

Sinner has been stripped of the prize money and ranking points he gained from reaching the semi-finals at Indian Wells, where he lost in three sets to eventual champion and rival Carlos Alcaraz.

However, the Wimbledon 2022 finalist Nick Kyrgios reacted with incredulity to the news, insisting Sinner’s positive tests warranted a sanction, irrespective of whether he was to blame.

Kyrgios wrote on X: “Ridiculous – whether it was accidental or planned. You get tested twice with a banned (steroid) substance…you should be gone for 2 years. Your performance was enhanced.”

Denis Shapovalov added: “Can’t imagine what every other player that got banned for contaminated substances is feeling right now.”