Birmingham Coty are determined to thwart Alex McLeish's hopes of taking the Aston Villa job.
The Daily Mail says Blues have gone on the attack against McLeish, threatening to put the manager on gardening leave to stop him joining Aston Villa and accusing their rivals of tapping him up.
A source close to City owner Carson Yeung said: "The owner will not accept these dirty tricks. We have done everything by the book and will not back down.
"The behaviour of Alex McLeish and Aston Villa is disgraceful. If Aston Villa wanted Alex, they should have approached the board of Birmingham and asked for permission to speak to him. We have supported him by bringing his transfer targets to the club, despite the relegation.
"We are not prepared to allow him to move. We would rather he goes on gardening leave than allow him to go to Aston Villa. Our fans deserve more than this."