Rio de Janeiro's accredited anti-doping laboratory has been stopped from conducting tests, just weeks before the Olympic Games open.
The World Anti-Doping Agency said on Friday it has suspended the lab's accreditation due to "non-conformity with the International Standard for Laboratories".
The suspension is an embarrassment to Brazil and Rio so close to the Summer Games, which open on August 5 after months of political turmoil and financial crises.
The failings of the Rio laboratory, known as Ladetec, have previously been exposed by WADA suspending its accreditation in 2012, after a false positive test result, and revoking its status in 2013.
Rio risks being without a home town lab during the Olympics two years after it was shut down during the 2014 World Cup.
No details of the laboratory's latest problems were specified.
"The suspension, which took effect on (Wednesday) when the Rio laboratory was notified, prohibits the laboratory from carrying out all anti-doping analyses on urine and blood samples," WADA said in a statement.
Samples collected from athletes in Brazil during the interim ban will be transported to a lab in another country for testing, the agency said.
"This will ensure that there are no gaps in the anti-doping sample analysis procedures; and that the integrity of the samples is fully maintained," WADA's incoming director general Olivier Niggli said in the statement.
Niggli added that the agency "will work closely with the Rio laboratory to resolve the identified issue."
The laboratory can appeal against the suspension to the Court of Arbitration for Sport within 21 days.
Fifa found a solution to being without a lab during the 2014 World Cup that cost hundreds of thousands of pounds.
Then, samples taken from football players were flown to be tested at a WADA-accredited lab in Lausanne, Switzerland. No blood samples missed the deadline of being tested within 36 hours of being given by an athlete.