The World Anti-Doping Agency has labelled Brazil's decision to stop testing its Olympic team in the build-up to Rio 2016 as "unacceptable".
The host nation's anti-doping agency was asked to halt its work by Brazil's sports ministry for most of July, prompting WADA to write to the Brazilian authorities demanding to know why testing had halted.
"At a time when the integrity of sport is on the line, it is vital that effective, rigorous testing is in place across the world..."
A WADA spokesman said that the Montreal-based agency was "very concerned" to learn that the second largest team at the Games was not being properly monitored at such a "crucial time".
"The response WADA received was unsatisfactory and the situation was unacceptable," the spokesman said.
"We informed the (International Olympic Committee's) pre-Olympic Games Task Force and immediately requested that they up the number of tests in order to prevent any further gaps in the process.
"At a time when the integrity of sport is on the line, it is vital that effective, rigorous testing is in place across the world so that the athletes and public have full confidence in sport."
Brazil's ministry of sport claims testing was only stopped between July 1-24 because WADA had suspended Rio's anti-doping laboratory and the nearest accredited laboratories in Colombia, Cuba and Mexico had been unable to help.
But a former senior official from Brazil's anti-doping agency has told The Times newspaper that he left the organisation because the sports ministry was asking him and his colleagues to do fewer tests.
According to Professor Luis Horta, a former boss of Portugal's anti-doping agency, the period without proper testing was 45 days.
"The sports ministry and the Olympic committee were putting pressure on us saying we were making too many doping controls on the athletes and this was causing a problem for their training," Horta told The Times.
"We were performing around three a year and in some cases on the best athletes as many as six in the last year.
"They also said we were too strict in the employment of the whereabouts system (that is used to locate athletes for no-notice tests).
"The anti-doping agency's primary objective was for many medals and all of them clean, and that's what's supported by the majority of Brazilians.
"But this goal was not shared by all parties: some just wanted many medals, whether clean or not."
Horta's comments have been categorically rejected by the Brazilian sports ministry but WADA has confirmed that it is investigating the matter.
Even if testing was only halted for three and a half weeks, the timing is terrible for an Olympics already reeling from weeks of intense debate about the Russian doping scandal.
It also highlights the limitations of WADA and its painfully-stretched resources - a #22m annual budget and staff of 70 simply cannot police the entire world, which means compliance with global anti-doping rules is ultimately a matter of trust.
