The centre-back confirmed this on his Twitter by saying "Sadly we were unable to negotiate and reach an agreement on an extension.
"Contrary to rumours I've not agreed to go elsewhere, I'm currently a free agent.
"I would like to take this opportunity to thank the club, the coaching staff, backroom staff and especially the fans who welcomed me into a great city.
"Wishing Notts fans all the very best for the remaining 18 games."