The international athletics federation's former chief Lamine Diack has been put under formal investigation in France on suspicion of corruption and money laundering, the French financial prosecutor's office said on Wednesday.
The probe comes at a time when the image of world sport's governing bodies is under serious scrutiny, with the FIFA world football body mired in a large-scale corruption probe.
According to French news channel iTELE, the investigation is focused on suspicions that payments were made in return for not revealing the doping of Russian athletes.
The prosecutor's office did not confirm that but said its investigation started when the World Anti-Doping Agency (WADA) alerted it to "acts of corruption and laundering involving members of the International Association of Athletics Federations (IAAF)."
Under French law, magistrates place a person under formal investigation when they believe there are indications of wrongdoing, but that does not always lead to a trial.
The investigation "concerns money movements and goes beyond doping," a source in the French judiciary said.
The Monaco-based IAAF confirmed a police swoop took place at its headquarters on Tuesday "to carry out interviews and to access documentation". It said it was fully cooperating with the probe.
Diack, a former long jumper who was born in June 1933, headed the athletics body for the best part of a decade from 1999. He was held for questioning on Sunday, together with his judicial adviser Habib Cisse, also placed under formal inquiry.
A doctor in charge of anti-doping matters at the IAAF was also held for questioning.
Reuters was not immediately able to reach the three men for comment.