The goalkeeper is a target for Aston Villa.
Speaking after his side's 1-0 win over Nice on Saturday, Warnock once again emphasised they are yet to receive an approach for the Philippines international, but refused to rule out a possible departure this summer.
"As I've said before, we'll listen to anything," he told WalesOnline.
"I've not heard anything and I don't think Neil has."
Asked if he was worried about Villa potentially stepping up their interest before the close of the window, he added: "Not really. I think we've got three great keepers.
"It wouldn't worry me playing any of three. Joe Day's had a fantastic pre-season, Smithies is as reliable as anything and Neil is what he is.
"So it wouldn't worry me if an offer came in for Neil, Smithies or whatever, because I'm very happy in that department.
"It's the other end of the field that I'm concerned with really."
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