Birmingham have launched a bid to sign Barry Bannan from Sheffield Wednesday, Sky Sports News understands.
However, the Blues have been told Bannan is not for sale before the transfer deadline on Thursday.
Sky Sports News reported last week that Hull City had seen an offer rejected for the midfielder.
The 27-year-old Scotland international joined Wednesday from Crystal Palace on a one-year deal in 2015 and signed a three-and-a-half-year contract extension in January 2016.
Bannan has become a fan favourite at Hillsborough in the last two seasons, making 87 appearances and scoring four goals.
He has made seven appearances for Wednesday this season and scored in the EFL Cup win over Chesterfield.