Sources said O'Brien has been crunching the numbers with a view to making a bid for the telco. But with Babcock & Brown now holding 28.8% of Eircom, and the Esot sitting on another 21.6%, O'Brien is extremely unlikely to make any kind of move unless the situation changes.

The stakeholders now both hold blocking positions that would bar any other suitor from crossing the 80% threshold after which the remaining shares could be compulsorily acquired.

Eircom is understood this weekend to be on the brink of opening the company's books to Babcock & Brown, with a stock exchange announcement coming more than likely this week.

The company has in recent days been finalising the conditions on which it would be prepared to let its Australian suitor carry out due diligence.

Burned before Christmas after Swisscom pulled out of a prospective takeover deal days after the Swiss company completed due diligence, Eircom chief executive Phil Nolan will be keen to impose stringent conditions on any future scrutiny of the books.

The Eircom side will be keen to ensure that the Australian company is in a financial position to go ahead with any takeover bid for the business.

Babcock & Brown has already signalled that it is likely to split the wholesale and retail arms of Eircom if a takeover goes ahead. It has also had talks with potential partners.

O'Brien recently declined publicly to rule out taking an interest in Eircom, which now looks closer to facing its fourth change of ownership in just seven years. The telecom entrepreneur's E-Island consortium lost out to the Valentia consortium led by Tony O'Reilly in the 2001 battle for control of the former state telco.

O'Brien has since built a successful Caribbean mobile phone business, Digicel, but sources said last week that he still regards Eircom as an attractive target back at home.

Analysts estimate that 1bn needs to be spent over the next five years to upgrade Eircom's network. But the company would still be seen by O'Brien as a plum prize. As well as control of 79% of the fixed-line market, the deal would also bring him back into the Irish mobile game through Meteor.