Birmingham have had a £6m bid for Robbie Keane accepted by Tottenham, BBC Sport understands.
The 30-year-old Republic of Ireland striker has been given permission to hold talks with City, although he is yet to discuss personal terms.
City have agreed to pay Spurs an initial £4m with an extra £2m coming via various add-ons in the deal.
Keane has found his chances limited at White Hart Lane this season, making 11 of his 13 appearances as a substitute.
Blues boss Alex McLeish has prioritised bolstering his forward line in the January transfer window with his current set of attackers struggling to find the net.
Only Wigan have scored fewer than Birmingham's 20 Premier League goals this term.
Midfielder Craig Gardner is the club's top-scorer with five goals while strikers Nikola Zigic, Kevin Phillips and Cameron Jerome have contributed a meagre eight goals between them.
Keane, who re-signed for Tottenham in February 2009, just six months after leaving the north London club for Liverpool, spent the second half of last season on loan at Celtic.
West Ham have also been interested in signing Keane.
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