Celtic are treating the leak of a document highlighting their transfer plans as a criminal matter.
The club have launched a "top-level probe" after details were shared and circulated online, according to the Scottish Sun.
The dossier is extensive in highlighting potential signings this summer as well as players in the team who will be available.
Both manager Neil Lennon and Celtic supremo Peter Lawwell have been made aware of the leak which is believed to be from a recruitment meeting back in April.
The club are preparing for a key transfer window with a number of players having left already following the conclusion of their loan deals or their contract has expired.
The future of Mikael Lustig is also still up in the air with the Swede weighing up offers from his homeland.
It is thought Lennon wants at least six players with the club linked to a number of players already, including Charlton midfielder Joe Aribo and Motherwell star David Turnbull.
It has previously been reported that former striker Gary Hooper is wanted by the Northern Irishman, while England youth internationalist Rekeem Harper has had a VIP tour on the club's trophy day when they defeated Hearts 2-1.