Villa confirmed on their website they are in discussions with their Premier League rivals about the player.
Warnock was an unused substitute in the Carling Cup victory against Gillingham.
He sat out the defeat by Sunderland at the weekend and remained at home as speculation mounted about his desire to leave Ewood Park.
Warnock has become a key player for Blackburn with his ability to play at full-back as well as in midfield.
Blackburn manager Sam Allardyce has already stated Warnock will only be allowed to leave for the right price.
"I think it is obvious he would like to move to a club of that size (Villa) without me trying to cover it up," Allardyce said earlier.
"The problem is we want the value we think Stephen is worth and that is the most important thing from my and this club's point of view."
Warnock moved to Blackburn from Liverpool in January 2007 after being frustated at a lack of first-team opportunities.
Such was his good form he was called into the England squad a year later, although he has not been able to build on his one cap.
Tottenham defender Pascal Chimbonda, meanwhile, is understood to be speaking to Rovers about a move from White Hart Lane.
The 30-year-old, who has struggled for regular football since returning to Spurs from Sunderland, can operate across the back four as well as in Warnock's left-back position.