Nicole Sapstead, the chief executive of UKAD, warned last week she would not sanction the release of blood and urine samples from Britain's four-time Olympic gold medallist, unless there was "credible evidence" to suggest they contained banned substances.

Former WADA President Sir Craig Reedie promised in November the organisation would "look at" athletes who trained under banned coach Alberto Salazar.

Salazar was found guilty of doping violations earlier this year, after a four-year investigation by the United States Anti-Doping Agency (USADA).

Following Salazar's ban, International Olympic Committee President Thomas Bach called on WADA to investigate athletes who had been associated with the Nike Oregon Project.

UKAD have claimed they are yet to receive a request from WADA for reanalysis of samples they hold, adding they would be happy to assist.

"UKAD has not refused any request from WADA," a UKAD statement read.

"To clarify, at this moment in time we have not received any request from WADA for reanalysis of samples we hold for any sportsperson.

"On the specific subject of the Nike Oregon Project, in November 2019 we proactively offered to assist WADA in their endeavours and to date we have received no such request for any assistance.

"We have been clear that we are happy to assist any anti-doping organisation including WADA.

"We want to reassure athletes that our active ongoing reanalysis programme takes many factors into account, including keeping samples from the most high-profile sports and the most high-profile athletes, and reanalysing them when new scientific developments take place, or analysis sensitivity improves, or if intelligence such as new information comes to light.

"We want to assure athletes and the general public that catching cheats and keeping sport clean is at the heart of what we do, and we have a wide number of robust programmes, including testing, investigations and education to protect sport.

"We comply with the World Anti-Doping Code, the international standards and the UK National Anti-Doping Policy and we do take action when evidence of wrongdoing comes to light."

UKAD had faced criticism from the Russian Anti-Doping Agency (RUSADA) for their alleged refusal to hand over samples to WADA.

UKAD played a leading role in helping rebuild the anti-doping system in Russia, following the publication of a series of reports which led to RUSADA being suspended initially by WADA in 2016.

So Mo tweeted that he was happy for any anti-doping body to retest any of his previous samples.

"I've seen reports of my name in connection to UKAD and WADA about sample retesting," Sir Mo wrote.

"Just to be clear, I was not consulted about this and as I’ve said many times, I am happy for any anti-doping body to test any of my previous samples anytime."

Farah, winner of the Olympic 5,000 and 10,000 metres gold medals at London 2012 and Rio 2016, has never failed a drugs test and has always strenuously denied taking banned substances.

The WADA said all options were open to the organisation as part of its investigation.

"The matter is ongoing so there's not much we can say except that our independent Intelligence and Investigations Department is in contact with USADA to review the investigation, as we committed to do," a WADA spokesperson said.

"All options are open to us, including requesting stored samples to be reanalysed."