He will be replaced as acting chief executive by the group’s chief financial officer Richard Moat with immediate effect.
Eircom said its board would now begin a selection process for a permanent CEO.
“During the past two years, Herb has led Eircom through a critical juncture of our transformation and overseen a network investment programme that has significantly upgraded our capability,” said Eircom chairman Padraig McManus, highlighting expansion of the company’s fibre network and 4G mobile service as key achievements.
However, Mr Hribar’s departure follows Eircom’s decision to pull a planned €1 billion stock market listing earlier this month.
The company had filed an initial public offering prospectus (IPO) with the Central Bank but later pulled back on this decision on the grounds that its shareholder-lenders had told management they did not support the idea.
The proposed IPO would have been the third time in 15 years that the company had gone to the public markets to raise funding.
Mr Hribar took on the role of chief executive when Eircom came out of examinership two years ago after creditors wrote off 40% of its more than €4bn in gross debt.
The funds raised by an IPO would have been used to pay down the company’s €2.4bn debt pile and would likely have valued the company at more than €3bn, according to reports.
A six-month long strategic review was undertaken by Goldman Sachs, Rothschild and JP Morgan that is believed to have weighed up both the proposed return to the markets and a trade sale of the company, neither of which now appear to be immediately on the cards.
In recent weeks a range of funds — including Apax Partners, CVC Capital Partners, and KKR — had been linked with a possible trade sale, as was American telecoms giant AT&T.
Mr Hribar would have benefited from a cash bonus under an incentive plan if either an IPO or trade sale had gone ahead, it has been reported.