Reports had suggested that Blues were close to completing the signing of Martins from Russian side Rubin Kazan on loan for the remainder of the season but McLeish has admitted that there is still work to be done before Blues secure the services of the Nigerian striker.
"We're trying to get him," McLeish said after the FA Cup tie against Coventry on Saturday.
"We're working hard on that but it's not a done deal yet."
McLeish also admitted that Racing Santander were interested in signing Blues striker Nikola Zigic but that no decision had yet been made between himself and the Blues board on whether or not to allow the Serbian striker to hold talks with the Spanish outfit.
"Santander have been in touch but we'll be together in the decision with the board as we always are," he said.
"I said after the midweek game (against West Ham) that it would be difficult to let Ziggy go on that kind of form."