Gibson claimed that agent Ian Elliott was playing "a dangerous game" and said it was unfortunate that the club even had to deal with him - branding him "a man who, in any other walk of life, you couldn't imagine giving ten minutes of your time to".
He labelled Elliott's demands over Downing's potential contract extension as "fanciful" and questioned whether the agent had the player's best interests at heart.
Today Elliott reacted angrily to the chairman's comments telling the Evening Gazette: "I spent all day yesterday taking legal advice because I feel the comments made by Mr Gibson were defamatory.
"My lawyers agree and we are just deciding on the next course of action.
"I'm disappointed with his comments. I have known Stewart Downing and his family for 10 years and I would never do anything that's not in his best interests."