Birmingham have confirmed the Football League have placed them under a transfer embargo after they failed to submit their club accounts on time.
The npower Championship club missed the March 1 deadline and consequently are now banned from any activity in the transfer marker until further notice.
They are the second club on Friday to have a transfer embargo imposed on them following midlands rivals Coventry earlier.
A Birmingham statement read: "Birmingham City Football Club can confirm that it has been made subject to a transfer embargo by the Football League. This is due to not hitting a 1 March 2012 deadline for submission of the company's June 2011 financial statements to the League.
"As has been widely reported, Birmingham International Holdings Limited is expected to publish the financial statements by the end of April 2012.
"The delay in filing the financial statements is occasioned due to the delayed audit processes, with both the club and the group holding company having to handle a series of audit issues, together with the financial issues thrown at the club due to the arrest and freezing of the assets of the club's main benefactor and changes to banking arrangements.
"The draft financial statements are prepared and it is understood that these will be finalised and published by the end of April (as previously announced through the Hong Kong Stock Exchange).
"This short period of delay in submission, and the resulting transfer embargo, does not affect the business of the football club at this present time.
"Having captured the signatures of several more players in the last couple of weeks, the club is satisfied with the strength and size of the playing squad, which has been sufficiently reinforced to assist with our end of season push."
Birmingham on Thursday signed three players, with Peter Ramage arriving on loan from QPR while Caleb Folan and Cian Hughton joined as free agents.