Bus Éireann has estimated that it would take at least 10 years to implement the decentralisation plan imposed on the company by the Government.
A report drawn up by the company's management and seen by The Irish Times also says the plan puts its business at "serious risk".
The company is due to transfer 200 staff to new headquarters in Mitchelstown, Co Cork, within three years under the Government's decentralisation programme. This is despite the fact that it currently has only between 80 and 90 staff at its Dublin head office.
In its report, prepared for the Department of Finance, the company says that in order to meet the Government's requirement it will have to recruit between 110 and 120 additional staff into its head office.
The timing of decentralisation, it adds, would depend on the number of existing management and staff volunteering to transfer.
"To date, during communication sessions with staff, nobody has expressed the wish to transfer to Mitchelstown," the report says.
"If all management and staff were to be replaced, the time-scale to achieve the transfer would be extensive, phasing would be essential and the time-scale would probably be not less than 10 years."
The report also includes a risk analysis which warns of a threat to the company's business should the move go ahead.
"The most serious risk created by decentralising the head office of Bus Éireann from Dublin to Mitchelstown is the continuity of the business.
"This risk would be very low if the majority of management and staff volunteered to transfer, but the opposite will be the case.
"Mitigation of this risk could only be effected by recruiting a similar number of management and staff, inducting them into the organisation and training them in roles on a one-to-one basis."
It is understood that the report was furnished to the Department of Finance in recent days. All agencies earmarked for decentralisation were required to prepare such "implementation plans" for the Department by the end of May. The report concludes that the process of decentralisation "will be extremely risky, costly and could only be effected on a long-term phased basis".
Mr Rodger Hannon, Irish secretary of the Transport Salaried Staffs' Association, which represents Bus Éireann's head office staff, said it was clear the plan to move the company to Mitchelstown was in serious difficulty.
Bus Éireann, he said, was already one of the most decentralised State organisations, with 85 per cent of its staff based outside Dublin. The report, he said, was "surely the last nail in the coffin" of the plan to move its head office to Mitchelstown.
Mr Colm Jordan, an official of the union, said if the relocation went ahead every staff member at the company's headquarters would be new and would have to be trained. "It is clear that more thought and planning have gone into party fundraisers than the decentralisation project," he said.
