The World Anti-Doping Agency has said that they are "very alarmed" by fresh doping allegations after a leak of test data.
The Sunday Times have gained access to the results of 12,000 blood tests from 5,000 athletes which reveal "the extraordinary extent of cheating" by athletes.
The investigation claims that a third of all medals won in endurance events at the Olympics and World Championships between 2001 and 2012 were by athletes with suspicious tests, and that seven British athletes recorded suspicious results.
Mo Farah, whose coach Alberto Salazar is accused of encouraging doping, recorded no abnormal results according to the investigation.
Russia are alleged to be the biggest offenders by the investigation, with over 80% of their medals won by athletes providing suspicious results.
