"Never did anything like that," McQuaid told Reuters.
Garmin Sharp manager Jonathan Vaughters claimed that McQuaid, who stands for re-election on Friday in Florence, asked an unidentified employee to ignore the team's instructions to cooperate with a US federal investigation in May 2010.
McQuaid, who has had to deal with the fall-out from the Armstrong doping scandal, was first elected in 2005 and is facing a stern challenge from Britain's Brian Cookson in his bid to secure a third four-year term.
The election will be held from 07:00 on Friday.
- Jonathan Vaughters