However, Clark has now admitted his interest in the 25-year-old, although he has insisted that no agreement between the Blues and Collison is close.
"He's just training with us, for a couple of days. I know his agent very well. When there is a player like Jack Collison on the open market, he is a terrific footballer, obviously there's going to be interest," Clark told the Birmingham Mail.
"I think he has got a deal in the offing from Ipswich which he is mulling over. Like I said, we're just having a look."
Collison has been capped on 17 occasions by Wales at senior international level.