Birmingham are considering making a complaint to the Premier League over Blackburn's interest in Robbie Savage.
Rovers have had a £2m bid turned down for the 30-year-old.
Now Blues owner David Sullivan has told The Sun: "It is quite clear Robbie has been tapped up and what Rovers are doing is highly illegal and improper.
"We would get the Premier League to ask for all the relevant phone records to prove they have been in contact with our player."
Sullivan added: "It is just not acceptable. We are not normally the sort of club to go
running to the Premier League crying 'foul'.
"We are becoming increasingly upset by it all, and if it carries on, we will
do what Southampton did to Aston Villa over James Beattie and complain to the
"Rovers can offer us what they want for him but as far as I am concerned any
bid they make will not be acceptable because we have no desire to sell him."
Blackburn chief executive John Williams told The Sun: "As far as we are
concerned we made an official approach that was rejected - and that is as far as
it has gone."
Savage has revealed family problems are behind his desire to join Blackburn.
"I have got real family problems back home and so has my wife," said the Wrexham-born midfielder. "These things all add up and people don't know the other side."
Savage's desire to join Blackburn has brought fierce criticism from the club's supporters.
But the 30-year-old added: "I have not been crying in anyone's office because the fans are bullying me."
Savage added: "I would never let anything get to me like that.
"It won't change me as a player but it still upsets me.
"I don't like people saying derogatory things about me. This is not about money.
"Whether I am at Birmingham, Wrexham or wherever, I just want to be close to my family."
Savage's father has recently retired through ill health and his mother suffered a stroke.