WADA launched an investigation following claims that the new-generation BEREG-KIT Geneva security bottles, made by Berlinger, could potentially be opened if a sample is frozen.

In a statement, WADA has confirmed they had found a "potential integrity issue" with the bottles.

The problem was not limited to samples which had been frozen, WADA added.

The IOC admitted they were "very concerned" about the issue with the Pyeongchang 2018 Opening Ceremony just over a week away.

The IOC had called on WADA to look into the matter after the problem was reported by a laboratory in Cologne.

In an update, WADA said the IOC should not use the new bottles at Pyeongchang 2018 and should continue to use the BEREG-KIT 2016, released for the 2016 Olympics in Rio de Janeiro.

"It has been confirmed that a proportion of the new generation BEREG-KIT Geneva security bottles are susceptible to manual opening without evidence of tampering, whether they have been frozen or not," the WADA statement read.

"These security bottles were introduced in September 2017 by Berlinger.

"WADA is currently ensuring that all potential causes for these irregularities are being explored and in the meantime has recommended to the IOC that for Pyeongchang 2018 they use the earlier model BEREG-KIT, which was first released in 2016 for use in particular at the Summer Olympic Games in Rio and which reported no such issues. 

"To that end, through its anti-doping partners, WADA has managed to source enough kits of the earlier model to cover the entire testing program in place for Pyeongchang."

The IOC have since confirmed they had been in contact with both Pyeongchang 2018 and the Doping-Free Sport Unit regarding the anti-doping operation at the Games, which begins with the Opening Ceremony next Friday (February 9).

"We understand they will follow WADA's recommendations," the IOC said in a statement.

WADA director general Olivier Niggli said the use of the earlier bottle was "a precautionary measure that guarantees the integrity of the doping control process at the Games".

Niggli added WADA had written to all anti-doping organisations and WADA-accredited laboratories to make them aware of the latest situation.

"For the longer term, WADA will continue to gather information and explore solutions with Berlinger and others in order to maintain the integrity of the process," Niggli said. 

"Berlinger has already agreed to restart production of the 2016 model pending other development.

"Where anti-doping organisations only have the BEREG-KIT Geneva security bottles available, rather than suspend testing, we are advising them to continue to use them in the short-term until stock of other kits can be obtained. 

"We have informed all WADA-accredited laboratories of an enhanced interim protocol to check the kits when at the laboratory that will further reinforce the process. 

"All of these measures are being put in place to ensure athletes continue to have confidence in the anti-doping system."

German journalist Hajo Seppelt claimed in a documentary on ARD that they had been able to open sealed containers "without trace".

It comes with the fall-out from the Russian doping scheme at their home Sochi 2014 Winter Olympics and Paralympics still continuing.

A covert operation to replace tainted samples with clean ones was supposedly in operation at the Games.