Nick Kyrgios has slammed an independent tribunal's decision to clear world number one Jannik Sinner of wrongdoing after he failed two doping tests earlier this year.

The International Tennis Integrity Authority (ITIA) said Sinner returned the positive tests in March.

The tribunal, convened by Sport Resolutions, accepted Sinner's explanation the anabolic agent clostebol entered his system from a member of his support team through massages and sports therapy.

Sinner said his physiotherapist Giacomo Naldi applied an over-the-counter spray containing clostebol to his own skin to treat a small finger wound.

Naldi then administered massages between March 5 to 13 without using gloves, according to the ITIA.

Sinner, who won this year's Australian Open, said Naldi was unaware the product he had used on his cut contained clostebol.

Clostebol is a steroid that can be used to build muscle mass.

Kyrgios, writing on social media platform X, lambasted the Sinner ruling

"Ridiculous — whether it was accidental or planned," Kyrgios wrote.

"You get tested twice with a banned (steroid) substance … you should be gone for 2 years. Your performance was enhanced."

Sinner's first positive sample was taken on March 10 with a second returned eight days later.

A provisional suspension was applied with each positive test, but he was allowed to continue playing after his team filed urgent appeals.

"Sinner's results, prize money and ranking points from the ATP Masters 1000 event at Indian Wells, where the player tested positive in competition for clostebol, are disqualified," ITIA said in a statement.

Sinner will lose the $US325,000 in prize money and 400 rankings points he earned in Indian Wells.

The 23-year-old, who has always maintained his innocence, said the amount of clostebol found in his system was less than a billionth of a gram.

"I will now put this challenging and deeply unfortunate period behind me," the 23-year-old said in a statement posted to social media.

ITIA chief executive Karen Moorhouse said Sinner and his representatives "fully cooperated" with her group's "thorough investigation".

The men's ATP Tour released a statement, saying it was "encouraged that no fault or negligence" was found on Sinner's part.

The World Anti-Doping Agency said it would review the decision and reserved the right to appeal.

Former top-10 player Denis Shapovalov questioned the decision to clear Sinner of wrongdoing, writing on X: "Different rules for different players."

Shapovalov added: "Can't imagine what every other player that got banned for contaminated substances is feeling right now."

But retired Australian professional John Millman defended Sinner, highlighting the amount of clostebol found in the Italian's system.

"Before jumping to conclusions, Jannik Sinner had less than a billionith of a gram in his system.. I believe him," Millman wrote on X.

Sinner won the Cincinnati Masters 1000 title on Tuesday, Australian time, ahead of the US Open, which begins in New York on Monday.

Reuters/ABC