Norwich have warned they will snub any approach for manager Paul Lambert.
Lambert is currently the bookmakers' second favourite for the Celtic job, with caretaker manager Neil Lennon's odds having lengthened since Saturday's shock Active Nation Scottish Cup defeat to Ross County.
Former Celtic midfielder Lambert, 40, has repeatedly stressed he has no interest in a return to the club and Canaries chief executive David McNally told BBC Sport: "If anybody came in for him, we would say, 'Your interest is not welcome, you do not have permission to speak to him, please go away'."
Lambert's stock has grown since taking over at Carrow Road in August and the club are on the brink of the Coca-Cola League One title.
McNally added: "Paul's very happy at Norwich City. He's got a job to do and I know he's looking forward to next season.
"Of course we all hope we'll be in the Championship. That will bring for all of us some real challenges but I am sure he's planning to take this great club forward."