Manager Walter Smith confirmed to evertonfc.tv: "The club and Abel have failed to reach agreement on a new contract - the club having offered a new three-year contract and Abel turning down the offer that was made.
"Negotiations have broken down recently, so what the club have decided to do, with the agreement of the player, is to place him on the transfer list immediately.
"That will mean he will be available to move at any time if a club comes in for him."
Xavier's current deal expires at the end of June this year, at which time he could leave the club for nothing under the Bosman ruling. Everton will be looking to get as much for avier as possible, and whilst no firm offers have been recieved for him yet, it is expected that he will leave the club within a month or so.