After potential issues with the security of the bottles were aired, the IOC has asked the World Anti-Doping Agency (WADA) to ensure that anti-doping tests at the forthcoming Winter Olympics in Pyeongchang "can be conducted credibly and reliably," an International Olympic Committee (IOC) spokesperson said Tuesday.

WADA has said it was alerted by the Cologne anti-doping laboratory on January 19 that the bottles "may potentially be susceptible to manual opening upon freezing of a sample." It has contacted the bottles' manufacturer Berlinger about the problem.

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"We have full confidence in WADA that a solution to this problem will be found," the IOC spokesperson said.

The head of the Cologne anti-doping laboratory, Mario Thevis, meanwhile said doping tests at the Games, which begin on February 9,  would be reliable despite the potential security issues.

"There are ways to ensure the integrity of urine samples," he told German broadcaster ZDF on Tuesday.

mp hf (AFP, DPA)