The 29-year-old, who is a Northern Ireland international, left Celtic on a free transfer this summer after failing to secure regular football last season.
"Birmingham have expressed an interest in Paddy and he has spoken to Lee Clark," his representative Leroy McCourt told Sky Sports News.
"There has also been interest from other Championship clubs as well as sides from Turkey, Australia and America. Paddy is weighing up his options and we hope to make a decision soon on his future."
It is believed that the midfielder favours a move to England.