"There's a package there that could lead up to £2million," he told BBC Scotland. "There's a certain amount guaranteed and a certain amount with add-ons.
"I'm not going to discuss what Rangers have bid because it's not right (to do so).
"Celtic have asked for permission to speak to the player, that was all, and that permission was given.
"Celtic know the price that we are asking.
"That price was a decision made by (Kilmarnock chairman) Michael Johnston and the board, that I agreed with.
"He's been fantastic in the Premier League for the last couple of seasons, he's also a full Scotland international and what we're asking for is fair."
"They are quite entitled to value a player at whatever they like, there's nothing wrong with that, but never at any time have Rangers met our asking price which they've known from day one.