A "thorough and aggressive review" needs to be done to protect clean athletes from "gangsters" after a blockbuster report surfaced alleging widespread doping in athletics, the head of the US Anti-Doping Agency said on Sunday.

Britain's Sunday Times newspaper and Germany's ARD/WDR broadcaster said they had obtained the secret data from the global athletics governing body, the IAAF, showing endurance runners suspected of doping have been winning a third of Olympic and world championship medals.

USADA chief executive Travis Tygart said he was unaware of any American involvement in the report but was disturbed by the allegations.