The Potters have not yet made any signings in the post-season transfer window but new boss Mark Hughes saw seven players released shortly after he was confirmed.

Despite their current lack of activity in the transfer market, it is believed that they are in line for a new defender.

"We are certainly looking for a left-back because we've only got Marc Wilson at the moment and he was brought in as a midfield player," Coates told The Sentinel.

"We haven't made any decision (on Pieters) because we are looking at options, but he's certainly a possibility."

The Netherlands international has been capped 17 times for his country but missed a lot of last season in the Eredivisie through injury and suspension.