LONDON • The UK Anti-Doping Agency (Ukad) has said it will not hand over distance runner Mo Farah's blood and urine samples to any investigation into the Nike Oregon Project, unless it is given credible evidence to suggest they might contain a banned substance.

The World Anti-Doping Agency (Wada) is expected to retest some samples of athletes from the training group, whom the Briton was part of between 2010 to 2017.

This is part of a new investigation into the now-defunct elite running programme that was announced in the wake of founder and coach Alberto Salazar's four-year ban for doping offences.

The US Anti-Doping Agency (Usada), which led the initial probe into the Cuba-born American, had also previously expressed an interest in getting hold of Farah's samples - a move resisted by Ukad.

Its chief executive, Nicole Sapstead, has said she would not agree to a "trawling expedition" without the evidence to back it up, as she wants to save any samples in its possession in case there are scientific advances in the future.

"We supported Usada in their investigation into the Nike Oregon Project," she said. "There has never been any ill-feeling or lack of willingness or assistance on our part.

"But when you open a sample up, every time you freeze it and thaw it and freeze it again, you are degrading the sample.

"I was simply saying to Usada: 'You need to be able to give me credible evidence about what it is you want to look for, rather than this just being a trawling expedition.'

"I'm not going to risk samples that we hold in storage that could enable us to retest when the science moves along."

Sapstead also hinted she would resist any order from Wada to hand the Farah samples over.

"We'll have to see whether that comes into play," she added. "My view is, any sample collected by Ukad is the possession of Ukad.

"If we collected on behalf of the IAAF, it's the IAAF's sample. If we collected on behalf of Usada, it's Usada's sample."

Four-time Olympic gold medallist Farah, who denies any wrongdoing during his career, has said recently he would have left Salazar's programme much earlier if he had known what he was up to.

THE GUARDIAN