The Daily Mail says Rovers are ready to step up their interest in Roger Johnson after he was told he can leave Birmingham.
The centre half's agent Paul Smith said: "I've had a call from Birmingham to say they'd let him go. Having played every league game for two successive seasons he will be in demand. It's just a matter of where he goes."
Despite his £14million price tag Johnson, 28, has attracted plenty of interest from Premier League clubs.