Sources said the decision to split has been coming for some time. Connolly had been deeply involved in O'Brien companies including Communicorp and Digicel.

Having closely worked with university friend O'Brien in getting Esat off the ground, Connolly advised on the major fundraisings carried out by O'Brien's companies, including presenting with him to raise the first �?�10m in institutional investment for Communicorp/Esat in 1994.

As well as sitting on the Communicorp board and holding a number of other group directorships, Connolly has been a director of mobile phone company Digicel, which just launched in Trinidad and Tobago, and for which he worked on raising more than $800m.

O'Brien was one of Connolly's two clients when he set up corporate finance boutique Connolly Corporate Finance in 1991. The other was Oliver Murphy of Hibernia Foods. Connolly had previously been financial controller of Hibernia Meats, whose planned flotation in 1990 was aborted after Saddam Hussein invaded Iraq.

His first big deal then came when Hibernia Foods floated on the Nasdaq in 1992 and raised $3m.

Connolly was a director of Esat until its sale to BT, from which he made nearly �?�8m.

Alongside growing his corporate finance business, he has since invested in a number of technology companies.

In 2004, he paid �?�30m for a 60% stake in the Thomas Read Group of pubs developed by Hugh O'Regan. He subsequently fell out with O'Regan over a court action taken by O'Regan against Bank of Ireland to secure an indemnity for the potential group tax debts.

Connolly recently emerged, in partnership with Citibank, as one of two private sector players that have made proposals to government to set up an overseas development bank in partnership with the state.