Birmingham will attempt to block Aston Villa's bid to interview Alex McLeish for their vacant manager's post after accusing their local rivals of tapping up the Scot.
Blues will today lodge a formal complaint with the football authorities about Villa's plans to speak to McLeish, who resigned from his position at St Andrew's on Sunday.
Villa believe McLeish is a "free agent" and they are therefore entitled to speak to the ex-Scotland and Rangers boss who quit after three-and-a-half years at City.
But Birmingham are seeking £5.4m in compensation from Villa to cover the remaining two years of McLeish's contract and have put the matter in the hands of their lawyers.
City, in a media statement said: "Birmingham City find Aston Villa's announcement to proceed with an interview with Alex McLeish a contempt of Premier League and FA rules.
"The club feel this will taint football and give the game and the footballing authorities a bad name if this is allowed to materialise.
"The club will do what is within its powers to prevent this and will lodge a formal complaint to the authorities on Wednesday as there is now not the slightest doubt remaining about this tap up attempt.
"Birmingham City stresses that this conduct, if condoned, will open up flood gates and set a very bad precedent."