Under-fire World Anti-Doping Agency (WADA) said on Thursday it would launch an independent review over its handling of a case that allowed 23 Chinese swimmers who tested positive for a banned substance to avoid punishment.

The investigation will be led by Swiss prosecutor Eric Cottier, a former attorney general of the canton of Vaud, who WADA said will have access to all files and documents related to the case and be free to consult any independent experts.