HITC Sport understands that NEC Nijmegen fear Venezuelan attacker could be set for move in this window.
Santos has been one of the sensations of Dutch football this season and already has 12 goals to his name, which follows on from 23 goals last season which helped NEC to promotion back to the top-flight
The 27-year-old has a buy-out of just 1million euros, and that has alerted a host of British clubs, with Celtic understood to be leading the chase.
But with some money in hand from the sale of Demarai Gray, Birmingham could manage to match the buy-out too and HITC Sport understands that the player is tempted by a move to England - whether it be Premier League or Championship.
Aston Villa and Hull City are also known to have scouted him in recent weeks, whilst a number of other clubs have been alerted to his progress and NEC are braced to lose him both the deadline on February 2nd.