It was revealed on Wednesday that the Potters were considering a bid for the striker, who has not played first-team football since August 2008.
The 25-year-old underwent ankle surgery earlier this year and is said to be nearing a return to training ahead of the new season.
Ashton signed for the Hammers from Norwich in 2006 for £7.25million and has made 46 league appearances since the move, scoring 15 goals.
Coates: "I think Tony has talked to West Ham. That is the stage we are at. Tony likes him as a player.
"We haven't really discussed Michael Owen at this stage. We know he is about. But I don't believe we have made an approach."