Robert Haulbrook, Meteor's highly-regarded chief executive, is believed to have told the board of Eircom that he plans to leave the company and return to his native United States.

It is understood Haulbrook has told Eircom's top brass that he wants to leave in April and return to the US for family reasons. His family has already returned to live in Atlanta.

It is expected that Haulbrook will be replaced by Larry Smith, who is the company's chief operating officer.

Informed sources say Haulbrook considered leaving the company around the time of Babcock & Brown's takeover in August but was persuaded to remain on.

Haulbrook (47) is credited with turning Meteor's fortunes around over the past few years from being a distant third-placed operator in the mobile market to a company with a 16.5 per cent share behind O2 and Vodafone.

It is believed to have about 800,000 subscribers at present, virtually all of which are pre paid customers.

Haulbrook's departure would be a blow to Babcock & Brown, which is currently seeking to raise the €114 million necessary to secure the final 3G mobile licence that is available from the government.

Eircom also needs significant additional funds for the rollout of a 3G network.

Pierre Danon, Eircom's chairman, and Rex Comb, the company's chief executive, are thought to have made strenuous efforts to persuade Haulbrook to remain with the company.

Eircom refused to comment when asked if Haulbrook was leaving.