Unions at An Post claim talks on a new partnership deal could be in jeopardy unless the company is forced to pay staff the full terms of Sustaining Progress.
With talks on a new national agreement expected to begin in the autumn, staff and pensioners at An Post are still awaiting pay rises due since November 2003.
Independent assessors appointed by the Labour Relations Commission recently recommended a 5 per cent increase, backdated to January 1st. This was accepted by the company and the increase is to be paid to all staff at the end of the month.
Unions, however, rejected the assessors' report and are continuing to seek payment of the full 8.5 per cent increase outstanding under the terms of Sustaining Progress.
An Post, which announced a €7 million profit last year after posting substantial losses in the previous two years, pleaded inability to pay the increase.
The second-largest union at the company, the CPSU, said that members are angry at the prospect of new national pay talks beginning when the existing agreement has "not been honoured".
Unless the full terms of Sustaining Progress are paid, it said, talks on a successor agreement would be "in serious doubt".
The CPSU and other An Post unions plan to highlight the issue at this week's biennial conference of the Irish Congress of Trade Unions (Ictu) in Belfast.
CPSU general secretary Blair Horan claimed the failure by a semi-state company to pay the terms of a national agreement was a "new departure".
"Other semi-state workers need to be warned that the State seems to be happy to allow those under its control renege on its obligations under the deal," he said.
The union claims that the assessors, who issued their report earlier this month, failed to take account of the "inherently uneconomic" social obligations placed on An Post and the costs involved in meeting them.
"The report copperfastens the company's apparent position that the workers, rather than the State, should cover these costs," said the union's An Post official, Eoin Ronayne. "If Ictu and the trade union movement generally does not address this problem in An Post now, all semi-state workers face a very uncertain future under any new national agreement which allows State-owned companies to plead inability to pay".
An Post has criticised unions for their refusal to accept the assessors' report, "particularly given the fact that it was the unions who sought the appointment of the assessors".
The independent assessors did not rule out full payment of the Sustaining Progress increases, but said the amount outstanding should be linked to work practice changes. These are due to be implemented as part of a rationalisation of the company's collection and delivery services that could involve up to 1,500 job cuts.
A Labour Court recommendation on these issues, based on a report by a panel including industrial relations consultant Phil Flynn, is due shortly.
A motion by the Public Service Executive Union, calling for recognition that the solutions to An Post's problems "cannot be borne exclusively by the staff", is to be debated at the Ictu conference.
