MONTREAL (AP) — The world’s top anti-doping regulator said after reviewing a television documentary and newspaper reports that it stands by its decision to clear 23 Chinese swimmers to compete at the Tokyo Olympics despite testing positive for a banned heart medication.

The World Anti-Doping Agency issued a statement Sunday following the release of a documentary on the cases by German broadcaster ARD.

In an earlier statement following initial newspaper reports, WADA said it agreed with Chinese authorities and ruled that the swimmers’ samples had been contaminated.

The New York Times reported that Chinese anti-doping authorities found the results of the tests were Adverse Analytical Findings but cleared the swimmers without any penalties after finding that the samples were flagged as positive as a result of contamination.

“Following WADA’s review of the documentary, the agency still stands firmly by the results of its scientific investigation and legal decision concerning the case,” WADA said in the statement Sunday. “We are equally confident that WADA’s independent Intelligence and Investigations Department followed up on all allegations received, which were not corroborated by any evidence; and thus, did not meet WADA threshold to open an investigation.”