Independent News & Media (IN&M) defended itself against accusations about the way the company is run at its agm in Belfast today.
It was respoding to a report published this week commissioned by businessman Denis O'Brien which which called into question the corporate governance of the international media group.
Mr O'Brien holds an 8.35 per cent stake in IN&M and his offensive was seen in business circles as the start of a possible bid for the group.
But former Canadian Prime Minister Brian Mulroney, an IN&M director and chairman of the company's corporate governance committee, led the counter attack.
He said: "This report was essentially unimpressive and unpersuasive. It was thrown together and contains serious mistakes."
He told shareholders: "Honestly, there was not a scintilla of evidence of impropriety or wrong doing of any kind."
Mr Mulroney added: "This company is as clean as a hounds tooth."
Mr O'Brien was not among the 200-plus people who attended the agm at a hotel outside Belfast, but questions were put during the re-election of independent directors by nominees from two stockbrokers.
Andrew Clearfield, of Merrion Stockbrokers Nominees, said: "I am concerned this is not an independent board, that committees are not independent."
He said four members of the O'Reilly family were on the board - making up one fifth of its directors.
He said: "The composition of the board seems to me to be more reminiscent of a wholly-owned family company rather than a public company."
Meanwhile, a statement released this evening on behalf of Mr O'Brien said the company had not responded to issues raised in the report.
The statement said: "Unfortunately the board of IN&M has failed abysmally to respond to and deal with the serious matters of corporate governance raised in the letters. These are matters we will return to."
The statement also said that in directors who were critical of the report at the AGM had "failed to identify the specific aspects of the Davis Report of which they were critical".
Shareholders appeared unimpressed with the interventions and went on to re-elect all independent directors who were up for re-election and to back the board in a number of motions.
In addition the company announced that former British home secretary and chancellor Kenneth Clarke (67) is to join the company's board of directors.
The company also said Baroness Margaret Jay has been appointed as the senior independent director.