The Biden administration’s top drug official called on Monday for an independent investigation into how Chinese and global antidoping authorities decided to clear 23 elite Chinese swimmers who tested positive for a banned drug months before the Summer Olympics in 2021.

The official, Rahul Gupta, who is the director of the Office of National Drug Control Policy, said that he planned to bring up the handling of the positive tests during a two-day meeting of sports ministers in Washington. Top members of the World Anti-Doping Agency are scheduled to attend the event, which starts Thursday.

“The United States stands by its commitment to ensure that every American athlete and those across the globe are provided a level playing field and a fair shot in international athletic competitions,” Dr. Gupta said in response to questions from The New York Times. “There must be rigorous, independent investigations to look into any incident of potential wrongdoing.”

Dr. Gupta is a member of the WADA executive committee, but he and his staff had not been briefed about the case involving the swimmers until Friday, according to a statement from his office. The next day, an investigation in The Times revealed the swimmers’ positive tests for a banned heart drug, trimetazidine, or TMZ, and the response to them by national and global antidoping officials.

The 23 Chinese swimmers were never suspended nor publicly identified before the Summer Olympics; at those Tokyo Games, they accounted for five medals, including three golds. The discovery that they had tested positive for TMZ but still competed prompted angry reactions from Olympians who raced against some of them, and charges of a coverup from others in the antidoping movement.

The call for an investigation from Dr. Gupta came as WADA held a video call with reporters to try to stem the fallout from the disclosure about the positive tests. In a virtual news conference that lasted nearly two hours, senior WADA officials and the organization’s top legal official repeatedly defended the handling of the case.

“If we had to do it over again now,” the WADA president Witold Banka said, “we would do exactly the same thing.”

Still, WADA acknowledged that its own protocols had not been followed in the case, confirming that, because of the pandemic, no hearings had been held with the affected swimmers to inquire about how the drug might have entered their systems. WADA said that it had decided not to appeal the Chinese decisions — including to not suspend the swimmers, as many antidoping experts said WADA should have — because the swimmers would have ultimately been cleared of any wrongdoing based on the available evidence.

And WADA reaffirmed that its officials had accepted — without independent verification — the findings of investigators from China’s state security services, who reported finding traces of the drug in a hotel kitchen but did not determine how it had gotten there.

To bolster their argument, WADA officials detailed what they said were extensive research and scientific reviews, including the engaging of trimetazidine’s original manufacturer to obtain nonpublic information from the company about the drug’s excretion periods — the time it takes to pass out of a human’s system.

A Chinese foreign ministry spokesman, meanwhile, responded to a question about the positive tests at a news conference on Monday by declaring the reporting “false information and reporting.”

The statements by top government officials — Germany’s sports minister has also called for an investigation after the public broadcaster ARD aired a documentary on the case — could make for an awkward two days of meetings this week in Washington.

That event, the annual convening of the Americas Sports Council, known by its Spanish acronym, CADE, brings together representatives from more than 40 countries and guests from across sports.

Among the officials scheduled to give presentations are Banka, the WADA president, and the organization’s No. 3 official, Olivier Niggli.

An email obtained by The Times shows that by April 2021 Niggli had been copied on an email about how the Chinese swimmers had tested positive. By that point, the Chinese had decided not to hold hearings or provisionally suspend the athletes, as antidoping experts have contended they should have.

The email — sent by an official at the Chinese antidoping agency, Chinada — was addressed to WADA’s director of legal affairs, Julien Sieveking. Mr. Niggli, who as director general serves as the agency’s top administrator, was copied on it.

As recently as March, Dr. Gupta spoke in glowing terms about WADA’s work in reforming itself in the wake of state-sponsored doping by Russia. But he cautioned about the ongoing risk of bad actors trying to undermine the global antidoping system.

“The efforts to reform and improve how WADA operates must continue,” Mr. Gupta said at an event hosted by the agency in Switzerland, after accepting an award on behalf of the public authorities — national governments — that contribute half of WADA’s budget. The United States is the highest single payer.

“WADA must stay ahead of this evolving threat because so much is at stake: from national pride to a great deal of money for victors and the dream of children around the world,” Dr. Gupta said.

world