Skysports.com understands Celtic have informed Derek Riordan he can leave the club in January.
Riordan has struggled to establish himself at Parkhead since his arrival from Hibernian in the summer of 2006.
The Scottish international has expressed his desire to move on in search of regular first-team action and Gordon Strachan is now ready to grant his wish.
The player's agent Jim McArthur has circulated Riordan's name to clubs in England and Scotland as Celtic prepare to listen to offers for the versatile forward.
Celtic are believed to be willing to sell Riordan for a nominal fee which has alerted a number of clubs.
One Premier League side and two Championships clubs are both believed to have enquired about the 24-year-old who is almost certain to move when the transfer window reopens next month.