The Rehab Group has accused the chairman of the Public Accounts Committee John McGuinness of being "grossly unfair" in his treatment of the charity and of causing it "serious harm".

In a statement tonight, it said it resented Mr McGuinness’s comments surrounding the receipt of a letter by the PAC containing allegations about “named individuals who have or had associations with the Rehab Group” and which he said could involve criminal wrong-doing.

The letter was received from Wicklow-based developer John Kelly.

“That the Chairman of Public Accounts Committee would comment publicly in this way on the allegations said to have been made, without having first given those persons who are said to be the subject of the allegations an opportunity to see the allegations, and to respond to them, is grossly unfair,” Rehab said.

"It has caused serious harm to the Rehab Group, to individuals within the Rehab Group, and to its employees."

The charity also said it was concerned the PAC had refused to furnish it with a copy of the correspondence.

Mr McGuinness could not be reached for comment.