O'Brien's audacious purchase of British media giant Emap's three Irish radio stations, Today FM, Dublin's FM104 and Donegal's Highland Radio, stunned some in the media world, particularly given the major potential competition hurdles the deal faces.

It had been widely expected O'Brien would show little interest in the stations, given the fact he already owned stakes in five Irish radio licences, including Newstalk and 98FM, and had built up an 8.6% stake in the country's leading newspaper group Independent News & Media.

The move, which one industry observer described as a "declaration of intent", raises questions about whether, in his quest to build his media interests, O'Brien has overstretched the financial resources of his radio holding company, Communicorp, which had accumulated debts of 30.3m in 2004, the final year for which accounts have been filed.

The Emap deal is the biggest acquisition in the company's history and is considerably larger than Communicorp's previous biggest deal, the acquisition of the Metromedia group's eastern European radio stations for 10.3m in 2004.

Paddy Halpenny, Communicorp's chief executive, subsequently described the move as "a brave jump" and it certainly was, given that even before the transaction the company's debt-tocapital ratio stood at 123.4%.

According to an analyst's report, seen by the Sunday Tribune, comparing the company to its peers, it is "significantly more levered" than its rivals. Its closest peer in terms of revenue and expansion, French group Nextradiotv, had a ratio of 59.5% in 2004, which had fallen from 75.1% the previous year.

By contrast, Communicorp's ratio had risen from 95.7% the previous year and it is likely to have risen significantly in 2005 and 2006, given that O'Brien funded the Metromedia transaction with a loan from Ulster Bank and has probably returned to his bankers for funding for the Emap purchase.

However, the company's 2005 accounts, which were due to be filed with the Companies Registration Office (CRO) in October 2006, have yet to appear.

This is particularly surprising given that O'Brien has clashed with the CRO before. In 1999, two of his companies, European Radio Corporation, which was the ultimate holding company for 98FM, and Brigadoon Media, which owned 30% of investment vehicle Radio Investments, were briefly struck off the register for failing to file accounts. The companies subsequently got their filing up to date and were restored to the register.

O'Brien is used to managing companies which are heavily in debt: his main business venture, Caribbean mobile-phone business Digicel, has accumulated debts of 1.8bn after a complex refinancing scheme last year that gave O'Brien complete control of the firm and an 580m profit.

The company, which had revenues of 686m last year, will need around 173m a year to cover the interest on its debts alone. However, Communicorp lacks its sister company's asset base and last operated profitably in 1996. The company's accounts also reveal O'Brien has been consistently lending millions of euro to keep the company afloat since 2001, giving it 4.6m in 2003 alone. By the end of 2004, Communicorp owed O'Brien 7.5m in interest-free loans that have no maturity date.

Although Communicorp only entered the bidding race for the Emap's stations in a surprise last minute move six weeks previously, O'Brien had made his Irish radio ambitions clear as early as 1989 with his now longforgotten bid for the state's first national radio licence, Radio 2000.

Radio 2000's aim was to produce a bilingual yet profitable national radio station, which aimed to "combine the best attributes of our heritage with a modern, forward-looking approach".

O'Brien's partners in the venture were Belfast's Downtown Radio, the Irish Farmer's Journal and cultural organisation Comhaltas Ceoltoiri Eireann.

He was also prepared to donate a 5% stake in the station to the state's main churches.

Despite this concession, the Independent Radio and Television Commission (IRTC), the forerunner of today's Broadcasting Commission of Ireland (BCI), opted for Century Radio's bid instead.

His Irish media ambitions frustrated, O'Brien moved into telecommunications and four years later, gained a telephone licence from the Department of Communications.

On 20 April 1994, Esat Telecom became Telecom Eireann's first domestic competitor, forming the basis of an Irish telecoms empire that O'Brien would ultimately sell to British Telecom in 2000 for 2.4bn at a personal gain of around 300m.

Despite his burgeoning success as a telecoms entrepreneur, O'Brien also began expanding his media interests abroad in the wake of the IRTC's rebuff, perhaps mindful of the fact that much of his early success was down to Dublin radio station 98FM.

Before O'Brien won the licence in 1988, his main venture was E-sat Television, which briefly operated a home shopping channel in the early days of Sky TV. Despite the backing of former RTE chairman Fred O'Donovan, the venture was a failure, losing �1m in its first month.

Dublin station 98FM, however, was an immediate success and provided a strong foundation for O'Brien's subsequent business forays.

Although Communicorp's official history states it was founded in 1989, the company only took its current name and form in 1994 when O'Brien's Esat Telecom was bidding for Ireland's second mobile-phone licence.

O'Brien used Communicorp as his vehicle during the licencing process and at one stage offered 98FM as security to obtain funding from Dermot Desmond's International Investment & Underwriting (IIU).

Under the proposed deal, Desmond would have had the right to purchase a third of 98FM for �1 if Communicorp failed to repay a �3m loan back by 31 March 1996.

O'Brien and Desmond failed to agree the loan deal containing this condition, although they subsequently reached a deal where IIU provided Communicorp with �6m towards its licence bid. It is unclear whether 98FM was offered as security for that transaction.

O'Brien's financial manoeuvrings paid off handsomely when Esat won the licence for just �15m after the then minister for communications, Michael Lowry, capped the bidding, a move which has been the subject of investigation by the Moriarty tribunal since 1997. Communicorp subsequently sold its telecommunications interests to Esat for �5.2m in a reorganisation of O'Brien's companies in 1996, leaving it as his main radio holding company.

By this stage, O'Brien was starting to build up a chain of radio stations in eastern Europe.

He was one of the first people to see the possibilities of commercial radio there after the fall of the Berlin Wall and reputedly even camped out in the streets of Prague awaiting the start of the licencing process in the Czech Republic in 1992.

Communicorp now has 12 stations in the Czech Republic with interests in Bulgaria, Estonia, Finland, Hungary, Latvia and Ukraine.

Much of its expansion in eastern Europe has come through the strategy of winning new licences, rather than acquiring them, a tactic which has been helped by the liberal licencing laws.

For instance, in the Czech Republic, companies such as Communicorp propose new stations and frequencies to the regulator. If the regulator agrees the proposal, a tender process for the licence then opens, which anyone can enter, although the proposing company naturally has a huge advantage.

In Ireland, despite O'Brien's Radio 2000 experience, Communicorp has expanded through applying for new licences with the backing of other respected media partners. In the case of Newstalk, it was part of a consortium of local radio stations while, for the Spin 103.8 bid, it enlisted the backing of UK dance music business Ministry of Sound.

However, in recent years, O'Brien has been quietly buying out his former partners: in 2005, Communicorp took outright control of Spin while earlier this year he completed the buying out of the final remaining minority shareholders at 98FM.

But there is one transaction that is likely to stand out in O'Brien's mind at the moment: in late 2003, Communicorp secured majority control of Newstalk by purchasing FM104's 15% stake in the station after Scottish Radio Holdings bought it and was compelled to dispose of its stake in the talk station to secure competition approval for the merger. It's a precedent which could come back and haunt O'Brien in the near future.