Investigators in the United States have asked for the samples of Olympic 10,000 meters gold medalist Mo Farah’s to be released by UK Anti-Doping (UKAD) so they can be tested across the Atlantic.

It has been reported that the US Anti-Doping Agency (USADA) chiefs have asked for the samples from the four-time Olympic gold medal winning long distance runner so they can be tested for blood-boosting substances.

It comes as questions continue to surround Mo Farah’s coach Alberto Salazar, who is accused of getting his athletes to take performance-enhancing drugs.

Salazar, who runs the Nike Oregon project, and the runner, have both vehemently denied all allegations that they are involved in breaking anti-doping laws.

USADA bosses believe they have enough evidence to re-test the samples of athletes involved with Salazar’s camp. One of the substances USADA investigators want to test for is EPO.

However, it is believed UKAD bosses are still waiting for more information from their American counterparts before making a decision.