Yeung has clinched a 29.9% stake in the club and it was thought the Hong Kong businessman would eventually buy out Sullivan and club chairman David Gold, but he believes it could be a long drawn-out affair - if it goes ahead at all - and he wants a decision by the end of September.
Sullivan told the Birmingham Mail: "I have to admit that I am concerned that this is all dragging on too long. It is not in the best interests of the club."
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