The director in charge of Eircom's networks and wholesale unit, Mr Herb Hribar, will step down next month.

The departure of Mr Hribar, one of the company's most experienced telecoms experts, is a blow for Eircom, which has turned around its wholesale business since he arrived in January 2002.

The firm is also losing another executive in its wholesale division, Ms Fiona Tierney, who is leaving to pursue other interests.

The departures come at a time when Eircom faces significant challenges over the next few months as several recent rulings by the Commission for Communications Regulation (ComReg) over network access take effect.

Mr Hribar took up the position as managing director of Eircom's networks and wholesale division in January 2002 following the takeover of the firm by a consortium of US venture capitalists chaired by Sir Anthony O'Reilly.

It is understood that Mr Hribar will return to the US to pursue other business interests. His responsibilities will be split between two existing executives.

Mr Peter Lynch, Eircom's chief financial officer, will take overall responsibility for the wholesale business and Mr Tony Wray will become Eircom's new director of networks.

An Eircom spokesman played down the significance of Mr Hribar's departure yesterday. "It was always expected that Herb would head back to the US following the end of the venture capital period at Eircom," he said.

"The transition arrangements have been in place for some time at Eircom."

However, Eircom's competitors will greet the departure of Mr Hribar with some dismay, given his role in opening the firm's networks to competitors.

Rivals acknowledge that Mr Hribar helped to changed the culture at the incumbent telecoms operator, which prior to his arrival had staunchly refused to develop its wholesale business.

Since his arrival, Eircom has increasingly enabled rivals to repackage its own broadband service to supply to customers. It has also enabled competitors to link into its network to better supply their business customers.

Although he was never a full board member at Eircom, Mr Hribar benefited from the grant of 1.4 million shares prior to its public flotation earlier this year.

Mr Hribar worked previously for the US companies Ameritech Wireless, Interliant and Verio.

Meanwhile, a second top executive in Eircom's wholesale division, Ms Fiona Tierney, is also leaving the firm.

Ms Tierney, is currently director of wholesale. She previously worked as head of Eircom's card and payphones unit and later as the firm's general manager of its hosting unit.