Serbian striker Milan Jovanovic will join Blues for £3.4million as long as they deal with agent Barry McIntosh rather than directly with Belgian club, Standard Liege, the McIntosh claims.
McIntosh insists he has an "exclusive" mandate from Liege to finalise a move for Jovanovic and that Blues face legal ramifications if they try to seal any deal directly with the club.
McIntosh told the Birmingham Mail, "They (Birmingham) can go and speak direct to the club (Liege) if they want but I have the exclusive mandate to get specific terms for the player, and that's come from their sporting director.
"That could have more [legal] ramifications if they did do that.
"I have managed to get Birmingham a fantastic deal for a player who absolutely destroyed Everton not too long ago in Europe.
"At the time there was talk of £10million offers, but Standard Liege didn't want to sell.
"Now he is coming to the end of his contract in June, and they have realised he doesn't want to re-sign, so they are looking to get the maximum price in January."
Jovanovic has scored 76 goals in 129 appearances for Liege and McIntosh added: "Jovanovic is a great talent. He can play coming in off the left or right, even though he is essentially left-footed, or straight up front.
"He has a presence, his goals record speaks for itself, and there are plenty of clubs out there who want him."