City chairman Peter Ridsdale commented: "In our situation as a Championship football club, we have to consider anything of this magnitude.
"Chris has indicated he wants to talk to them and we have given him permission.
"I think with the price itself we would have had to consider it no matter what the situation was financially.
"Clearly given the challenges we've had, it's made the financial security of the club more acute that we do look at this sort of transfer.
"But if Chris had said he wasn't interested in going, we wouldn't have sold him."
Gunter made his Bluebirds debut back in August 2006 in a Carling Cup tie against Barnet, while he made his full debut for his country in May this year in a friendly against New Zealand.