Denis O'Brien's plan to float Digicel on the New York Stock Exchange comes at a time of rapid growth for the Carribean mobile business he set up a couple of years ago after he made his first fortune with Esat.

The company does not make information about its financial performance public, but information circulated recently to bondholders suggests that a huge increase in subscriber numbers puts the company on course to take in annualised revenues of $1 billion (€788 million) when its current financial year ends next March.

The figures show that turnover rose to $204 million in the three months to June from $141 million in the same period in 2005. Excluding $5 million in once-off costs in Curacao, earnings before interest tax depreciation and amortisation in the quarter came in at $74 million. This compared with $62 million in the same quarter last year.

Quarterly operating profits stood at $46 million, up a shade from $45 million in 2005.

The flat performance at the operating level reflected higher depreciation charges after expensive launches of the Digicel service in Trinidad & Tobago and in Haiti.

The openings there in April and May helped to bring subscriber numbers to 2.6 million in June, up by almost a million from 1.7 million in the same period last year.

In Haiti, the company has already signed up half a million subscribers. When Mr O'Brien sold Esat Digifone to BT for for £2.5 billion, in 2000 it had only 700,000 subscribers.

Digicel has decided not to proceed with a proposed acquisition in Colombia. But overall investments now stands at $1.3 billion, and further expansion is expected in coming weeks as preparations for an initial public offering gain pace.

Only weeks ago, Mr O'Brien raised $150 million for Digicel in a new bond offering.