Published Friday, 14 December 2012
Health Minister Edwin Poots said the decision comes "against a background of very serious and unresolved issues with the performance of the Trust on emergency care".
Mr Stewart had accused the DUP minister of trying to victimise him after he threatened heads would roll if trusts did not achieve their targets.
Mr Poots said the comments were wholly inappropriate.
He has now terminated Mr Stewart's contract with immediate effect.
A written statement to the Assembly by the Health Minister continued: "Whatever may or may not have been said before 10 December, it was wholly inappropriate for Mr Stewart to speak publicly as he did on Monday.
"His statement was very damaging to the reputation of the Trust and confirmed that Mr Stewart does not share my view that much better performance against the 12-hour standard for A&E Departments is both possible and essential in the short term. I have brought in the Turn Around and Support Team to help ensure that the required improvement is secured."
Mr Stewart said the move is "unjust" and he is being made a "scapegoat".
He told UTV: "I believe I am being made a scapegoat by the minister who has set unreasonable targets and then threatened them to deliver.
"It's not really the way we should be running the health service.
"The Health Minister has been 18 months in the post and he has never once sat down with me to discuss issues with the trust or my performance or any points I have to make.
"This is very unjust."
The trust has been under mounting pressure, due in part to the services at Antrim Area Hospital's accident and emergency department.
The hospital has regularly missed waiting time targets for successive winters.
Mr Poots continued: "I firmly believe that public service values must be at the core of health and social care.
"Non- executive members who are appointed to the boards of health and social care bodies are placed in positions of responsibility and as such must demonstrate the highest standards of corporate and personal conduct based on recognition that patients and clients always come first.
"Regrettably, in addition to a number of performance issues at the Northern Health and Social Care Trust, upon which the chair was recently challenged by my department, Mr Stewart fell short of these high standards in recent days.
"I have therefore taken all factors into account and decided that in the interests of the organisation that his position as chair should be terminated."
Meanwhile the Northern Trust has wished Mr Stewart well for the future.
A statement said: "The Board members of the Northern Health and Social Care Trust wish to thank Mr Stewart for his years of commitment and contribution since the Trust was established.
"We are grateful for his strong leadership in contributing to the improvement of care for patients, clients and carers. The Minister has acknowledged the professionalism and dedication of all staff working at the Northern Trust and we welcome this.
"The Board wishes Mr Stewart well for the future."
© UTV News