"To reiterate what we've said on many occasions, we only accepted Jason's written transfer request reluctantly," Baggies chairman Jeremy Peace told the club's official website.
"Jason is contracted to this club until 2006 and we believe he is a player with outstanding potential.
"Therefore, we will only sell him if an acceptable offer is forthcoming.
"We have never named a price for Jason to any club but Wigan's bid is not even remotely in the ball park for what we would accept."