French prosecutors have confirmed they are probing a decision by the International Association of Athletics Federations (IAAF) to hand the 2021 World Championships to Eugene.
The city, in the U.S. state of Oregon, was awarded the event in April this year without the usual bidding process that is associated with awarding big events even though the Swedish city of Gothenburg was also interested.
Now the French authorities have told CNN Sport they are investigating the decision to anoint Eugene, as part of its investigation into former IAAF president Lamine Diack.
It said: "The national financial prosecutor ... has opened a preliminary investigation in order to determine the conditions under which the city of Eugene was designated and whether corruption, money laundering, criminal conspiracy offenses have been committed in France on this occasion."
Sportswear giant Nike has its origins in Eugene -- it was founded by two former University of Oregon students, Phil Knight and Bill Bowerman, in 1964.
The company still has links with the university and did have with IAAF president Seb Coe until recently when he relinquished an ambassadorial role.
French prosecutors said an email between a "marketing executive of a sporting goods company" to a member of the Eugene bid team had been the starting point for its investigation, launched on December 1.
It said the email related to the support of one of the vice-presidents of the IAAF, who was "also ambassador of the above mentioned sporting goods company."
The IAAF told CNN Sport it would reopen the bidding process should any corruption be uncovered by the French but insisted it stood by its decision to award the games to Eugene.
The organization has been under siege since French police announced they were investigating Diack on corruption and money laundering charges in early November.
It is alleged the Senegalese accepted around $1.09 million from the Russian athletics federation to conceal positive doping tests. CNN was unable to reach Diack for comment.
A report from former IAAF president Dick Pound released in Novembe
r claimed Russia had effectively run a state-sponsored doping program and that the IAAF had adopted an "inexplicable laissez-fair policy."
Russia has subsequently been suspended
from athletics and may not now be able to compete at the 2016 Olympics in Rio.
Eugene's 2021 bid leader and head of Tracktown USA in the city -- Vin Lananna -- was not immediately available for comment, nor was Nike.
But USA Track and Field (USATF) told CNN it stood behind the "merits of the bid, and our actions and efforts followed all ethical standards and norms for presenting bids."
It added: "We received excellent, positive feedback from (the IAAF) when we presented the bid for 2019, having narrowly lost the vote to Doha. We are pleased and honored to host.
"The Eugene bid was based largely on the notion that the United States is well positioned to host a World Championships, and that the sport would benefit worldwide from the Championships being held in the world's biggest sports sponsorship market and global economy."
Bjorn Eriksson, who was head of the Gothenburg 2021 bid, told CNN Sport he welcomed the French investigation.
"What I was very upset about was that the process wasn't transparent, we didn't get a chance, they decided in advance that we were not worthwhile listening to and that is unprofessional," he said.
"I don't think we've been given an explanation at all. The question I am putting forward time after time is why wasn't the process transparent and why were we not given a chance?
"We would accept to lose if we are evaluated in second rather than first but we are a bit insulted by the fact they didn't listen to us and I've found no acceptable reason for that behavior.
"That doesn't mean its criminal, it's just that it is at least unethical."
"We've had no contact from the prosecutors in recent weeks regarding Eugene," an IAAF spokesman told CNN Sport. "IAAF would reopen the bid if there was any wrongdoing in the decision."
The spokesman added: "We have no relationship with Lamine Diack since being charged by prosecutors, prosecutors forbid both parties to communicate with each other.
"IAAF stands by their decision to award the 2021 World Championship to Eugene."