AR 6-4-1-I (per the 2008 book anyway and assuming you meant A89 not B89)
A Team A player catches a free kick, thus preventing an opponent from making the catch. RULING: Illegal Interference.
I'll make the same assumption that you are talking about A89 (from the kicking team) catching the free kick.
Rule 6-4-1 states that "a player of the receiving team within the boundary lines attempting to catch a kick, and so located that he could have caught a free kick or a scrimmage kick that is beyond the neutral zone, must be given an unimpeded opportunity to catch the kick."
There is no stipulation that this only applies if a fair catch signal is given (that only matters if the receiver muffs the kick, they are then given the opportunity to complete the catch), so both situations are identical and should both be ruled illegal interference, B1/10 at A26.
From experience, this usually happens on an onside kick and is not easy to see for the official on that side of the field. This is when the official on the other side (F or S) needs to step up and help!!!