The World Anti-Doping Agency (WADA) has suspended the accreditation of the Brazilian Doping Control Laboratory in Rio de Janeiro just 42 days before the start of this year's Olympic Games.
Procedural errors are thought to be behind WADA's decision, which raises the possibility that samples collected during Rio 2016 will have to be shipped off and tested and analysed elsewhere at a cost of as much as $250,000 (£182,000/€224,000).
This was the case ahead of the 2014 FIFA World Cup in Brazil, where samples were analysed over 9,000 kilometres away in Lausanne in Switzerland.
It is thought a similar procedure would be much more difficult during Rio 2016 due to the volume of samples taken at an Olympic Games.
Outgoing WADA director general David Howman has described the news as "disturbing" in an interview with New Zealand-based website stuff.co.nz.
He claimed it was unlikely the problem will be rectified before the Games get underway with the Opening Ceremony due on August 5.
"This lab produced a whole list of false positives, and falsely accusing people is top of the pile of serious issues," Howman told stuff.co.nz.
The facility has encountered numerous problems in the past after it had its accreditation revoked in 2013 as it failed a "blind" quality assessment test.
In 2012, it was suspended from conducting isotope ratio mass spectrometry (IRMS) testing on samples for several months before being reinstated.
"Rio 2016 is totally committed to clean Games with a full anti-doping programme," a statement from Rio 2016 read.
"We are working together with WADA and the Brazilian Government to ensure this."
The suspension came into effect on Wednesday (June 22) and the facility is prohibited from "carrying out all anti-doping analyses on urine and blood samples".
The Laboratory has the right to appeal to the Court of Arbitration for Sport within 21 days.
Olivier Niggli, who is due to succeed Howman in the role of director general within the organisation on July 1, stressed WADA would only lift the suspension when it is "operating optimally" but claimed it will not have a negative impact on the extensive drug-testing scheme expected to be carried out during this year's Olympics.
"In the meantime, WADA will work closely with the Rio Laboratory to resolve the identified issue," Niggli said.
"The Agency will ensure that, for the time being, samples that would have been intended for the Laboratory, will be transported securely, promptly and with a demonstrable chain of custody to another WADA-accredited laboratory worldwide.
“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.
“Athletes can have confidence that the suspension will only be lifted by WADA when the Laboratory is operating optimally; and that, the best solution will be put in place to ensure that sample analysis for the Rio Olympic and Paralympic Games is robust.”
WADA will now put a Disciplinary Committee in place to review the case of the Rio Laboratory, which will then issue a recommendation to the Executive Committee.
If they decide not to remove the suspension, it will officially not be used to carry out sample analysis during Rio 2016 as the ban would then stay in place for a minimum of six months.
The news comes after the Madrid Doping Control Laboratory suffered a similar fate earlier this month.
Facilities in Madrid, Bloemfontein, Beijing and Lisbon are also currently suspended, along with the laboratory in Moscow.
They had initially suspended the facility on November 10, following the WADA Independent Commission reports which revealed evidence of widespread state-supported doping in Russian athletics.
Cover-ups and the destruction of samples were also revealed, and suspending the laboratory, which is at the centre of the scandal, was a key recommendation.
Its accreditation was completely revoked but WADA President Sir Craig Reedie then exclusively revealed to insidethegames last month that it had been partly re-accredited to enable it to resume analysis of blood samples.