The 31-year-old has himself hinted that he could move south to England in the summer to be closer to his children after the breakdown of his marriage.
But his agent Jonathan Barnett believes the player is ready to see out the remaining two years of his contract at Parkhead, dismissing a recent link with Swansea.
He said: “He has got two years remaining on his Celtic contract so why wouldn’t he see that through? He is enjoying his time up there. I have been reading and listening to speculation for the last 10 years or more but if I believed everything that I read, heard and saw then I would be mad.
“I have not heard about Swansea but it would be totally stupid to think he could go there.”
Portsmouth have also expressed an interest in the former Coventry, Wimbledon, West Ham and Arsenal frontman.