BANGKOK • Thai badminton star Ratchanok Intanon broke down in tears and spoke of her relief yesterday after being cleared of doping, ending fears that her Olympic dreams had been scuppered.

The 21-year-old shuttler, who is beloved in Thailand and remains the kingdom's best chance for a medal in Rio, tested positive for a banned substance during the Uber Cup tournament in China in May.

But the Badminton World Federation (BWF) yesterday cleared her after ruling that the substance had been administered to treat a tendon injury and was allowed.

"I was confident in my innocence and I am glad that I received justice. I will practise and hope to bring a medal back for the Thai people," she told reporters at a press conference in Bangkok.

"The Olympics is my dream," she added, before bursting into tears.

Rumours of the positive test result first surfaced in the Thai media last week, leaving fans on tenterhooks.

In a statement published yesterday, the BWF said Ratchanok tested positive for triamcinolone acetonide, a corticosteroid which is banned in most circumstances.

However, if administered directly into a muscle tendon for medical reasons it is allowed under the BWF's rules.

"The panel concluded that because the route of administration of the substance in the medical treatment process was intratendinous - an authorised administration route - no violation of the regulations was committed," the BWF said.

Patama Leeswadtrakul, president of the Badminton Association of Thailand, said doctors had been treating Ratchanok for pain in her right hand and back. "We said it was used honestly to cure her injuries," she told reporters.

Ratchanok has charmed the Thai public - who affectionately call her Nong May - with her girl-next-door demeanour despite the fame and riches of sporting success.

In 2013, she became the youngest-ever world champion. She was briefly ranked No. 1 after winning the Singapore Open in April but has since slipped to fourth.

A medal favourite in Rio, she will carry the Olympic hopes of a country with few top-class athletes. She will also be one of the chief threats to China's chances of another sweep of all five badminton titles.

The shuttler has caught the imagination of the Thais as much for her rags-to-riches back story as on-court heroics.

Her parents are migrants to Bangkok from the country's poor north-east who worked in menial jobs at a badminton centre on the outskirts of the city.

While they worked, Ratchanok played badminton, unlocking her talent at the age of six.

In a recent interview with AFP in Bangkok, she said she was "100 per cent confident" of bringing home a medal from the Rio Olympics.

Fans congratulated Ratchanok on her Instagram account, where she had recently posted a picture of the stars with the cryptic caption "I'm faded" as the doping rumours swirled last week.

"The sky after a storm always shines," one fan wrote.

Another added: "You're not faded, you are now brighter."

AGENCE FRANCE-PRESSE, REUTERS