Investigation begins as Kenyan doctors claim they gave British athletes performance-enhancing drugs

UK's Anti-Doping have said the claims are "of grave concern and significant interest"

Two Kenyan doctors' have been secretly filmed claiming to have given performance-enhancing drugs to British athletes.

In the footage filmed by the Sunday Times, the medics say they've treated them with the banned blood-booster EPO.

It's claimed to have happened near the British team's high-altitude training base in Kenya.

According to the BBC, Kenyan officials have made arrests in connection with the claim and UKAD (UK's Anti-Doping) have sent two investigators to Nairobi to help with the investigation.

A statement issued by UK Athletics urges newspapers to "provide full details of all of the individuals and information in its article as a matter of urgency so that the claims can be investigated in a timely manner" but also claims the allegations are "vague and unsubstantiated."

The newspaper claims the doctors provided blood tests and reports to confirm that they had in fact treated a British athlete for injury.

UK Athletics' Anti-Doping Chief Executive Nicole Sapstead said they have reviewed the evidence presented and says it is "of grave concern and of significant interest."

"We have opened an investigation and are taking the necessary steps to corroborate the evidence and investigate it further."