Unions at Iarnród Éireann have warned of a potential all-out strike later this autumn if the company does not concede a pay increase for staff.

However, the company has signalled that it remains at risk of insolvency, with accumulated debts of €160 million, and losses for this year forecast at €6 million.

Arriving for the opening of five weeks of intensive negotiations at the Workplace Relations Commission, SIPTU Assistant Industrial Organiser Paul Cullen said staff were seeking flat pay rises in line with recent increases or between 2.75% and 3% per year elsewhere in the transport sector.

He noted that passenger numbers were up, and that revenue had also increased, adding that staff had not had an increase in ten years, and had also taken a pay cut during the economic crisis.

He said the National Transport Authority was the "elephant in the room" - and that both the NTA and the Department of Transport, Tourism and Sport would have a role to play.

If the talks failed, he said, unions would seek a mandate for industrial action.

National Bus and Rail Union General Secretary Dermot O'Leary said that Iarnród Éireann could not continue to say it has no money for pay rises, yet "fanfare" that it has the highest passenger numbers ever, and revenue beyond Celtic Tiger levels.

He too warned of strike action if the talks failed.

However, Iarnród Éireann Director of Human Resources Ciarán Masterson said the company was prepared to review efficiencies and savings to meet the unions' aspirations for a pay rise.

He acknowledged that an all-out strike would damage customer confidence but said they had to deal with the simple fact that as an organisation they remain under threat of insolvency and must ensure they can continue to pay staff and run services going forward.