"We've had some enquiries from Villa over the last few days and they've come up with an offer which we think is acceptable to us," Boro boss Gareth Southgate told the club's official website.
"Sometimes an offer can be one that makes it very difficult to turn down.
"Nothing has gone through yet so I don't want to talk too prematurely about anything but Luke's down there having talks and I would imagine undergoing a medical and we wait to see what happens from there.
"Until everything's sorted out I don't want to talk about Luke in the past tense as he's still our player at this moment in time time."