The Kazakh rider is alleged to have paid rival Alexandr Kolobnev €150,000 (£120,000) not to contest the sprint of the prestigious Liège-Bastogne-Liège classic in April 2010
The claim was made by Italian newspaper Corriere della Sera who built upon allegations original made by Swiss magazine L'illustra.
Corriere della Sera published emails between the two cyclists that seem to show the two riders agreed to let Vinokourov win after it was clear they were the only two contenders near the finish of the race.
The emails show the riders exchanged bank details while the Swiss authorities have provided details of transfers between the two mentioned accounts.
Vinokourov won the race for the Astana team by six seconds from Team Katusha's Kolobnev with the rest of the field over a minute back.
The first of the alleged emails was sent the day after the race and it was from Kolobnev to Vinokourov. The Russian wrote: "Remember well, I had a great chance … I didn't do it for the contract but rather for the situation you found yourself in … if it had been someone else in your place I would have raced for the win, for the glory and the bonuses … now I'm waiting patiently. Take my transfer information and put them somewhere else and erase the email."
Vinokourov is said to have responded: " Hi Kolobok, sorry that I took so long to respond. Don't worry, you did everything right … as far as the agreement goes, don't worry, I'll take care of everything."
Corriere say these was then followed by two transfers from Vinokourov to Kolonev – one for €100,000 in 10 July 2010 and one for €50,000 on 28 December of that year.
Investigators claims they have "undeniable proof" of the fix and details have been sent to Belgian authorites and the UCI.
Vinokourov is a controversial figure in cycling and served a two-year ban after being found guilty of doping.
The allegations are a fresh blow to a sport keen to rebuild a culture of fairness after its biggest name Lance Armstrong was banned for life after indicating that he would not challenge charges that he had doped throughout his career.