A former chief investigator for the World Anti-Doping Agency said on Monday that the organization was “broken beyond repair” and had misled the public following disclosure of its decision not to discipline 23 elite Chinese swimmers who tested positive three years ago for a banned drug.

The investigator, Jack Robertson, said in a five-page statement that the agency’s handling of the positive tests and its response to the criticism it has faced demonstrated that it needed to be completely restructured to become “truly independent.”

Mr. Robertson said the agency, known as WADA, had made false and defamatory statements about how its top critic — the United States Anti-Doping Agency — handled a separate and complex doping case. WADA’s accusation that the American agency had mishandled the case and had been hypocritical in criticizing WADA came amid an escalating feud between the two agencies over whether WADA is capable of policing doping in international athletics.

“WADA has gone from enforcer to appeaser,” Mr. Robertson said.

He said: “To return WADA to what it was originally crafted to accomplish, a truly independent restructured agency needs to be instituted in its place, free of corrupted puppeteers.”

In releasing the statement, Mr. Robertson, who left WADA in 2016 and has been critical of its handling of other cases, became one of the most vocal former antidoping officials to take their concerns public in the wake of the revelations in recent months about the positive tests among Chinese swimmers.

The U.S. Anti-Doping Agency has been at the forefront of criticizing WADA since The New York Times reported in April that WADA declined to discipline the swimmers after they tested positive for a banned heart medication. WADA in effect accepted a Chinese explanation that the swimmers had unwittingly ingested small amounts of the drug through a hotel kitchen where traces of the medication were later found.