Chief executive Peter Lawwell has played down speculation linking Celtic with a host of players and has vowed to keep the club's transfer targets under wraps.
The Bhoys have been linked with moves for Euro 2008 stars Martin Stranzl, Khalid Boulahrouz, Alexander Frei and Jerko Leko, while Scotland international James McFadden has been mentioned as a possible arrival at Parkhead.
"I can assure supporters that we are working hard once again to strengthen the squad for the coming season," he told the club's official website.
"We have only made two bids for players, one of which was accepted for Patrick McCourt.
"Any other claims that we have made bids for other players are nonsense.
"Clearly, we do have our own real targets and we are working to secure these.
"As is the case in every close season, particularly with Celtic, press speculation has linked many names with the club.
"While the club chooses to conduct its business quietly and in private, there is very little we can do about this speculation.
"However, it should be said that there have been numerous players mentioned who have never interested the club and who we have had absolutely no contact with."