Paris - The former general secretary of the IAAF confirmed to AFP on Wednesday that he had written two letters in 2009, "among many others", to the Russian federation warning them about a worrying number of doping cases.
Pierre Weiss, who held the position at the International Association of Athletics Federations at the time, said the two letters were sent in June and October 2009, "so before and after the Berlin world championships" of August that year.
The letters, revealed by the Associated Press news agency, warned about the health risks being taken by the athletes taking part in blood doping and urged the Russian authorities to act.
"It is true that we have had a recurring problem with doping in Russia," Weiss said.
"The only difference between the current situation and the situation when I was there, is that I was a long way from imagining that the Russian federation was complicit or even taking the initiative."
The IAAF provisionally suspended the Russian athletics federation in November over a bombshell report by a World Anti-Doping Agency (WADA) independent commission alleging state-sponsored doping and mass corruption in the sport.
Russia is now trying to clean up its act amid fears that its track and field stars could be sidelined from this summer's Rio de Janeiro Games.
The IAAF said Russia could only be reinstated if it fulfilled strict criteria outlined last month, including compliance with all WADA and IAAF anti-doping rules and requirements.
It said that the Russian athletics federation must "clean house" by showing that none of its directors, officers and staff "has any past involvement in doping" and "must sever ties with anyone who cannot meet this requirement".
Further Russian athletics "must introduce a comprehensive code of ethics and reasonable term limits for all of its officials moving forward".
The WADA independent commission publishes its second report in Munich on Thursday, with co-author and former WADA president Dick Pound promising it to be more explosive than the first.