Bus Eireann's services to rural communities would have to shut down completely if it had not cut some of its services to the south and south east, the semi-state's chief executive said.
Martin Nolan issued the stark warning yesterday following the company's recent decision to cut almost 100 local bus services.
The affected routes were part of Bus Éireann's Expressway service. The decision to cut two routes entirely, Routes 5 and 7 -which served a number of rural towns and villages in Wexford, Wicklow, Carlow, Kildare, Kerry and Cork - has sparked outrage.
Mr Nolan was criticised by members of the Oireachtas Transport Committee who said the company had effectively "dropped the hatchet" on rural Ireland.
In his opening remarks, Mr Nolan said the Expressway service does not receive any public service obligation (PSO) funding and that although the Expressway service had turned a profit of just under €500,000, some routes were losing "thousands of euro" every week, meaning they were not commercially viable.
He said the "increasing liberalisation" and "cherry-picking" of routes by private operators threatened the survival of the Expressway service and the jobs of 500 workers.
"As a company, if we do not make changes required by customers, Expressway will go out of business and jobs will be lost, both within Bus Éireann and among the wide range of suppliers that depend on Bus Éireann across the country," Mr Nolan said.
He added: "We cannot trade recklessly. Expressway has to make a commercial return on its Expressway routes to enable fleet replacement to take place as it does not receive any funding for buses or coaches on these routes."
He declined to say how much had been saved by axing the services when questioned by Fine Gael TD Patrick O'Donovan and insisted the company had been faced with the choice of "coming out of some of these places (rural communities) or shutting down in total."
National Transport Authority (NTA) chief executive Anne Graham said a replacement service for Route 5, which goes from Dublin to Waterford via Wexford, had been found.
Efforts to find an alternative for Route 7, serving Cork and Kerry, are ongoing and a "working group" made up of local representatives has been formed to examine the issue.
She added that the NTA was "well-placed" to carry out reviews of services provided and "would continue to carry out reviews".
Independent TD Michael Moynihan said Bus Éireann needed to rethink the recent cuts.
He said by not retaining services now, which may become profitable down the line, the company had "killed the goose that may have laid the golden egg".