The World Anti-Doping Agency (WADA) has recommended the Winter Olympics in PyeongChang use an older version of doping sample bottles after concerns were raised about the latest model.
The recommendation, made to the International Olympic Committee (IOC), came after it was confirmed a portion of the new generation bottles are susceptible to manual opening without evidence of tampering, whether they have been frozen or not, WADA said.
Previously it was thought a problem existed with the newer bottles only when they were frozen.
The Winter Olympics begin on February 9.
The IOC was not immediately available for comment but earlier had said it was concerned about the new bottles.
"At this stage, our clear recommendation to the IOC is that it continue to use the earlier model, which is still used by a number of testing authorities around the world," WADA director-general Olivier Niggli said.
"This should be seen as a precautionary measure that guarantees the integrity of the doping control process at the Games."
WADA said it had managed to find enough kits of the earlier model bottles used at the 2016 Rio Games to cover the entire testing program for PyeongChang.
WADA began an investigation into the new model, released in 2017, after the accredited laboratory in Cologne, Germany, had discovered they may potentially be susceptible to manual opening "upon freezing".
Anti-doping agencies had turned to newer bottles after a major doping scandal at the 2014 Sochi Olympics.
