City had enquired into the possibility of ending the 23-year-old keeper's season long loan deal with Blues because of injuries to Shay Given and Stuart Taylor but their request has been denied.
They have instead been allowed permission to sign a goalkeeper on an emergency loan deal and Sunderland's Martin Fulop has moved to City for the remainder of the campaign.
“The Club, with the backing of the Premier League, have been in contact throughout the day with both Birmingham City and Sunderland with regards to bringing either Joe Hart or Marton Fulop to the team on an emergency basis,” a City spokeswoman told the club's official website on Tuesday evening.
“Agreement has not been reached with Birmingham, but we anticipate that Marton Fulop will join us in training tomorrow and we thank him and Sunderland AFC for their help in this situation.”