The World Anti-Doping Agency on Tuesday rejected the clean chit given to Indian wrestler Narsingh Yadav by the National Anti-Doping Agency in August, when he tested positive for a banned substance.

WADA has appealed to the Court of Arbitration for Sport against the Indian body's decision. The hearing is supposed to be held in Rio on August 18, one day before Yadav's scheduled bout at the Olympics. Yadav is considered one of India's more promising medal hopefuls.

"WADA has appealed against the NADA clearance in Court of Arbitration [for Sport]. Now the hearing is on and the IOA Secretary General [Rajeev Mehta] is there with WADA officials," said Rakesh Gupta, the Indian Olympic contingent's chef-de-mission.

Yadav was cleared of the doping charges in August by NADA, which said he was a victim of sabotage. If found guilty by WADA, Singh faces a ban of four years.