Bus Éireann has told staff it is pressing ahead with implementing cost-saving measures in two weeks without union agreement.
Management has been seeking reductions in overtime shift and premium payments, longer working hours for office staff and reductions in annual leave since last June.
The Labour Court issued a recommendation last February that accepted management's argument that the viability of the company could be in jeopardy, and recommended a set of cuts.
However, management has said it has been unable to secure projected savings from staff terms and conditions because of trade union resistance.
A spokesperson for Bus Éireann said it had no choice but to remind employees that unlike the wider public sector, Bus Éireann has no safety net and if it does not reduce its cost base, job losses could be unavoidable.
The company also warned that any industrial action would only exacerbate its difficult financial position and staff might have no jobs to return to.
It said that under February's Labour Court recommendation, there will be no cuts to core pay or employment levels.
Bus Éireann said the cuts are required because of a 20% fall in passengers due to the recession, rising fuel costs, a 25% cut in State funding and competition from private operators.
SIPTU official Willie Noone said staff in Bus Éireann were furious at the company's announcement that it is pressing ahead with cost-saving measures without union agreement.
He said the company was forcing them into a ballot for industrial action at the earliest opportunity.