The 29-year-old Brazilian was found to have traces of the performance-enhancing drug ostarine in his urine following a routine test.
He will face a tribunal hearing and could be banned for up to four years if found guilty, a Xinhua report said.
The AIU did not disclose when the sample was taken.
Braz competed in two Diamond League events in Europe in July and is preparing for the World Championships in Budapest next month.
Braz won gold at the Rio Games in 2016 and took bronze in Tokyo five years later. He also claimed the silver medal at the World Indoor Championships in Belgrade last year and holds the indoor and outdoor Brazilian pole vault records.
–IANS
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