Skysports.com understands Liam Ridgewell is waiting on the club to finalise his new contract at St Andrews.
Ridgewell has been in talks with the club for the last few months over a new deal with his current contract due to expire in the summer.
The 25-year-old has established himself as a key member of Alex McLeish's side since his arrival from bitter rivals Aston Villa in the summer of 2007.
Ridgewell has been an impressive performer for Birmingham this season, helping them form one of the meanest defences in the Premier League.
The former England Under 21 international is thought to have agreed terms on a new contract a while ago, but the club have yet to tie up the deal.
The news could alert interested clubs to Ridgewell's possible availability with the versatile defender a free agent in the summer.