The International Cycling Union pledged Monday to open its own probe into revived allegations that the London Games gold medallist from Kazakhstan paid off his opponent in a two-man breakaway to ensure he won the 2010 Liege-Bastogne-Liege classic.
The UCI acted after receiving a file on the case from an Italian prosecutor who is leading a wider investigation of corruption in cycling linked to Dr. Michele Ferrari, a former adviser to Armstrong.
"The UCI takes these issues extremely seriously," the governing body said in a statement provided to The Associated Press. "We will ask Alexandre Vinokourov and Alexandr Kolobnev to attend a meeting at our headquarters in Aigle as soon as possible to provide the UCI with their response to the contents of the Padua inquiry dossier."
Vinokourov allegedly paid Russian rider Kolobnev €150,000 (nearly $200,000) after arranging a fix during their breakaway in the April 2010 one-day race.
The allegations were first made by a Swiss magazine last year, and were denied by Vinokourov who threatened to take legal action.
Italian daily Corriere della Sera published further details Saturday, including details of emails it claimed were exchanged by the riders in the days after the race.
"The UCI has been requesting information concerning these media allegations since December 2011, when they were first raised by the Swiss magazine L'Illustre," the governing body said. "To date, the information provided to UCI was not sufficient to take legal action.
"Now, in the light of this additional information, gathered as part of the Padua inquiry, we will open an official inquiry into this issue."
The probe could reveal further corruption at the top of professional cycling as the sport struggles to deal with the Armstrong doping affair.
Padua prosecutor Benedetto Roberti helped the U.S. Anti-Doping Agency in building the case which led to Armstrong being stripped of his seven Tour de France titles last month.
Vinokourov finished third to Armstrong in the 2003 Tour, the fifth of the Texan's seven straight wins in cycling's biggest race. Those titles were formally stripped by the UCI after American anti-doping officials released a report that accused him of leading a massive doping program on his teams. No riders will be upgraded in the standings from 1999-2005 when almost all the podium finishers were later banned or implicated in doping schemes.
The Liege-Bastogne-Liege victory was Vinokourov's biggest after returning from a two-year suspension for blood doping at the 2007 Tour. He won the Belgian race with a long sprint to the line, finishing six seconds ahead of Kolobnev.
The Padua dossier reportedly includes a first email sent April 26, the day after the race, from Kolobnev to Vinokourov.
Payments to Kolobnev of €100,000 and $50,000 are reportedly detailed in the file from Padua prosecutor, who is investigating alleged money laundering linked to Ferrari. The Italian sports doctor is serving a life ban from cycling.
Vinokourov retired from professional cycling soon after winning the road race in London in July. The 39-year-old rider, who won road-race silver at the 2000 Sydney Olympics, has iconic status in his native Kazakhstan and has been expected to pursue a career in national politics.
If the UCI probe leads to sanctions for Vinokourov, the International Olympic Committee could examine whether he should have been eligible to race in London. He beat Rigoberto Uran of Colombia in a sprint after the two broke clear in the closing stages.
Vinokourov has been expected to take a senior management role with his Kazakh-based Astana team, which could also be sanctioned by the UCI if the allegation is proved. Kolobnev's Russian team Katusha also faces scrutiny.
"If this inquiry reveals any team involvement, according to the rules, the UCI may also ask the License Commission to re-evaluate the awarding of UCI licenses to Team Astana and Team Katusha," the governing body said.
"The UCI is absolutely committed to examining all issues arising from the Padua investigation constructively and transparently to safeguard the integrity of the sport."