The University of California, Los Angeles (UCLA) Olympic Analytical Laboratory has been partially suspended by the World Anti-Doping Agency (WADA).
The suspension of the lab, effective from June 14, is for a period of three months and a result of "WADA's quality assessment procedures that identified non-conformities with best practice".
Los Angeles is bidding for the 2024 Olympic and Paralympic Games, and has proposed UCLA as the venue for their Athletes' Village.
The laboratory is not located on the main campus of UCLA, however, but around three miles away.
No further details have been revealed.
During the suspension, the UCLA Laboratory can continue carrying out all of its regular anti-doping activities but must gauge another opinion on four substances.
"The Laboratory must obtain a second opinion from another WADA-accredited laboratory prior to reporting any adverse analytical finding (AAF) for the glucocorticoids prednisolone and ‘prednisone and the anabolic steroids boldenone and boldione," a WADA statement said.
"This type of suspension, which is limited to certain substances or classes of substances and that has been applied to other WADA-accredited laboratories in the past, allows for appropriate monitoring of the UCLA Laboratory to ensure full implementation of necessary improvements with the objective of a return to full compliance."
The UCLA Laboratory was notified of the decision on June 16 and may appeal at the Court of Arbitration for Sport within 21 days.
As part of the process, WADA will conduct a UCLA site visit within a time-frame that "reasonably allows the laboratory to finalise implementation of all remedial actions".
Founded in 1982 after a grant from the Los Angeles 1984 Olympic Organising Committee, the UCLA facility was the first American Laboratory accredited by the International Olympic Committee.
Don Catlin formed the Laboratory and served as its director for 25 years.
Catlin is best known for being the man that developed the test for the detection of Tetrahydrogestrinone that led to a number of athletes linked to the Bay Area Laboratory Co-Operative, including Britain's Dwain Chambers and the United States' Marion Jones, being caught in one of the biggest doping scandals in history.
Disgraced American cyclist Lance Armstrong also employed Catlin in an effort to prove his innocence back in 2009, when he was initially dogged by rumours that he used banned performance-enhancing drugs
UCLA provided anti-doping testing at Los Angeles 1984, Atlanta 1996 and Salt Lake City 2002 - three American editions of the Olympic Games.
At 60 hectares, LA 2024's proposed Athletes' Village at UCLA would be the second most compact in the last six Summer Games.
Fifty-one per cent of Olympians and 62 per cent of Paralympians would be able to train at the Village, with all others training at their competition venue.
The United States Anti-Doping Agency released a statement insisting that anti-doping practices within the country are still reliable.
"WADA’s announcement regarding the UCLA Laboratory doesn’t mean that there should be any concern about the reliability of anti-doping processes in the United States," it read.
"The UCLA Lab is still accredited by WADA and will continue to process samples for all prohibited substances and methods, as usual.
"It’s important to note that there have never been any false positives, or any suspicion of false positives, at the UCLA Laboratory.
"Moreover, no athlete has been wrongfully suspended or disciplined.
"Clean athletes can rest assured that their rights and the integrity of the sample analysis process are being upheld at WADA-accredited laboratories in the United States.”
Scott Blackmun, the chief executive of the United States Olympic Committee, backed the decision by WADA.
"We’re completely in favour of strict compliance with the code," he said in a conference call, responding to a question from insidethegames.
"To the extent that any laboratory is non compliant, whether it's in the US or otherwise, we support the direction that WADA has taken."
insidethegames has contacted Los Angeles 2024 for comment.