The big Guinea international told the Daily Record: "I had contact with Roy Keane on the last day of the transfer window and they wanted me at Sunderland.
"I wanted a permanent contract, not just three or four months, but (chief executive) Peter Lawwell could not find a way to let me go permanently.
"I don't know what was wrong but if Celtic don't want me I will leave.
"However, it has to be clear that I will leave in the way I want and not how Peter or other people want.
"If you are not wanted then you leave but I have two years left on my contract and I will leave the way I want and when I want if it is the right time for me."