The World Anti-Doping Agency (WADA) has opened an investigation into a potential integrity issue with security bottles used in drug tests.

WADA has been informed by an accredited laboratory in Cologne, Germany, that new generation security bottles, introduced in September 2017, may potentially be susceptible to manual opening upon freezing.

The bottles, made by Swiss manufacturer Berlinger, are used to collect, transport and store urine and blood samples for athletes' doping controls.

WADA said in a statement that it would "recommend appropriate measures, if needed, in order to maintain the integrity of the doping control process".

The statement continued: "WADA acknowledges that this situation, if confirmed, will raise concerns and questions.

"We wish to reassure athletes and other stakeholders that WADA is resolutely committed to following up with Berlinger until the matter is resolved; and that we will keep stakeholders apprised as the situation evolves."

The issue of bottle security was highlighted when WADA investigator Richard McLaren found that samples from the 2014 Winter Olympics in Sochi were tampered with as part of Russia's state-sponsored doping programme.

Russia have subsequently been banned from next month's Winter Olympics in Pyeongchang by the International Olympic Committee (IOC). Russian athletes who have been cleared by the IOC will be able to compete as an "Olympic Athlete from Russia".