Management at An Post has sought the immediate intervention of the Labour Relations Commission (LRC) to try to secure agreement on Christmas mail deliveries.
The move was made yesterday as a row erupted on a separate front over the company's decision to close its SDS parcel and courier service.
The Communications Workers' Union (CWU), citing a consultants' report, claimed the decision was based on flawed financial projections and called for an independent inquiry.
Executives of the company called a press conference to reject the allegation and accused the union of "not living in the real world".
In another development yesterday, the company confirmed that it was set to break even this year, despite previous assertions that it was heading for significant losses.
The changed forecast was mainly down to a €20 million saving from its decision to withhold the pay increases due under Sustaining Progress, it said.
Regarding the threat of disruption to Christmas mail deliveries, the company said it had failed to reach agreement with the CWU on operational arrangements such as overtime.
It sought the immediate intervention of the LRC with a view to having a deal in place by next week.
The move coincided with a separate row between the company and the CWU yesterday over the decision to close SDS and reintegrate its services into the main An Post group, with the loss of 270 jobs.
The union released a report it commissioned from consultancy firm LHM Casey McGrath, which questioned the basis on which An Post revised its 2004 revenue projections for SDS from €69 million last February to €63 million in July.
The board's July forecast required "further review" in light of an SDS forecast, in the same month, that turnover for the year would be €68.1 million, the consultants said.
The SDS forecast, which had been partly substantiated by actual turnover figures for July and August, "ought to have been available to the board" when it made the decision to close the division, their report added.
The figures were relevant, it said, because a €68.1 million turnover would confirm that performance levels had been sustained for the year and revenues had stabilised. It would also more than halve a projected loss for the year of €10 million.
Responding to the union's claims, An Post's commercial director, Mr Derek Kickham, said revenue was only part of the picture. The fact was that SDS had fixed costs that were unsustainable in a sector in which profit margins were 2-5 per cent.
Mr Larry Donald, chief operations officer, said: "The company, which has dealt with this matter and knows more about it than anybody else, and which has all the information available to it, is absolutely standing over the figures in relation to SDS."