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Athletics is bracing itself for another dark day with the World Anti-Doping Agency on Monday due to publish its report into allegations of widespread doping among Russian athletes.
Earlier this week French police revealed former International Association of Athletics Federations (IAAF) president Lamine Diack was being investigated over an alleged payment of more than one million euros to cover up doping offences by Russian athletes.
It then emerged the IAAF ethics commission had brought disciplinary charges against four men, including the son of Diack and the former head of its anti-doping department.
Monday's publication is set to bring the matter to a head.
Richard McLaren, one of the authors of the independent report, has been quoted as saying it will be "a real game-changer for sport" and that it will demonstrate "a whole different scale of corruption" even compared to the FIFA scandal.
Lord Coe succeeded Diack as IAAF president in August and, asked f or his reaction to the situation, told BBC Radio 5 Live's Sportsweek programme: "Clear shock, a great deal of anger and a lot of sadness.
"These are dark days for our sport but I'm more determined than ever to rebuild the trust in our sport. It is not going to be a short journey.
"The day after I got elected, I started a massive review. Understandably, in the light of the allegations that have been made, that review has been accelerated and I am determined to rebuild and repair the sport with my colleagues.
"But this is a long road to redemption."
When it was put to WADA president Sir Craig Reedie on Sportsweek that the report was likely to cause shock, he said: "I think there's been a great deal of speculation.
"I think it will be very robust in terms of what it was set up to do, which was to examine serious breaches of doping rules in Russia, and the anti-doping community and sport should be ready for that."
There has been talk of the possibility of Russia being thrown out of the sport, and Coe said on that matter on Sunday: "I've never said never, but my instinct here is engagement rather than isolation.
"If we want change, and this is not just about processes and procedure, it is cultural.
"We need a generation of athletes and coaches who believe it is absolutely possible to reach the pinnacle of our sport and do it with integrity, as clean athletes. "
Coe said he did not know but that it "may well" prove to be the case that nations other than Russia were involved in the situation.
He added: "Will we ever have a clean sport? No.
"There will always be people in any walk of life who will step beyond the moral boundaries.
"It is our responsibility to make sure we have the right systems in place - and the right people in the organisation upholding those systems."