THE departure of the north's most senior civil servant and a permanent secretary could spark a shake-up among the heads of Stormont's departments.
Sir Malcolm McKibbin will step down as the head of the regional civil service at the end of January after nearly six years in the job.
The Executive Office said his successor would be appointed through an "open external competition".
The announcement came 48 hours after the Department of Education said permanent secretary Paul Sweeney planned to retire at the end of the year.
Mr Sweeney has headed the department since February 2010, and prior to that was permanent secretary at the Department of Culture, Arts and Leisure.
News of the high-profile departures came as former BBC journalist Stephen Grimason announced he was retiring from his job as the executive's director of communications.
The appointment at the same time of David Gordon, editor of Radio Ulster's Nolan Show, to a new role of executive press secretary was questioned this week by opposition parties.
The Executive has confirmed the £75,400 post was not advertised, but said Mr Gordon is not a civil servant and was recruited in line with regulations governing public appointments.
The Commissioner for Public Appointments yesterday said it was not aware of the appointment until it was publicly announced.
"It was not clear what or if any process was followed by the department."
Sir Malcolm was appointed somewhat controversially in 2011 through an internal trawl from a pool of just 10 department permanent secretaries.
In the past 18 months, he has overseen a reduction in the number of Stormont departments from 12 to nine and, according to the Executive Office, reduced the "size of the civil service by 17 per cent" through a debt-funded voluntary exit scheme.
First Minister Arlene Foster said: "Over the past five years, Sir Malcolm has been instrumental in helping to lead and reshape the Northern Ireland Civil Service and his leadership has displayed the best attributes of our public servants."
She thanked Sir Malcolm, as did Deputy First Minister Martin McGuinness, who said the departing civil service head had "served ministers and the entire executive with integrity and inpartiality".
“He provided sound and constructive advice to ministers and over the last few years, was heavily involved in the various political talks between the executive parties, including those which resulted in both the Stormont House and Fresh Start agreements," Mr McGuinness said.
Sir Malcolm said it had been an honour to lead the civil service against a "challenging backdrop of increasing demand and finite resources".
The announcement of his departure came 48 hours after details emerged of Department of Education permanent secretary Paul Sweeney's plans to retire.
In 2014, the retirement of Stephen Peover from the Department of Finance and Personnel triggered a series of reshuffles across departments and it is thought Mr Sweeney's departure may have a similar knock-on effect over the coming months.
