Sunderland once Darren Bent hits 50 appearances for the Midlands club.
The Villa manager also revealed that he has not received any transfer enquiries for the out-of-favour striker, and that the England international has not yet handed in a transfer request.
The 28-year-old has made 47 appearances and has not featured in either of the last two matchday squads following his return from injury.
Christian Benteke appears to have now established himself as the club’s number one striker as Bent has to watch on from the sidelines.
The speculation over the payments started when Jordan Bowery was preferred as a substitute to Bent for Tuesday night’s game against Reading.
Lambert defended his decision, telling the Shields Gazette: “Have there been any enquiries for Bent? No. Has he asked to be put on the transfer list? No.
“Is there a clause? That’s not true. I’m not sure where that came from.”
When asked why Bowery is being preferred as a substitute, Lambert said: “I see what happens every day in training. I see with my own eyes what goes on.
“Jordan Bowery’s potential is extremely high, and he is an unknown quantity which sometimes can work in your favour. I see every day what goes on.
“We’ve got 20-odd guys in the same boat together which I pick from.
“I answered about 105 questions (on Bent) the other night. The team I pick will be the team that will go and try win us the game and that’s the way I’ll always be.”