Only three out of four items of ordinary mail are delivered by An Post the day after posting, according to a new survey.
Just 70 per cent of post in Co Dublin and 75 per cent in the rest of the country gets next-day delivery, the TNS mrbi survey found.
The figures contrast sharply with research commissioned by An Post, which shows next-day deliveries at 87 per cent for the first quarter of 2003, and at over 90 per cent for other periods.
A spokesman for An Post said the study, published yesterday by the Commission for Communications Regulation (ComReg), was based on an "immature" monitoring system.
"There needs to be a longer period of time before one can say it's reliable," he said.
But ComReg chairwoman Ms Etain Doyle suggested the TNS mrbi research was more accurate, given it measured only the performance of single piece mail.
"In contrast, the results of the quality of service monitoring published in An Post's annual reports measures the performance of all domestic mail, including bulk mail."
Furthermore, she said, the new study - the first of its kind, and limited to the first quarter of this year - took 400 sampling points compared to An Post's 150.
The company's performance is to be raised in forthcoming discussions between ComReg and An Post, which has applied to the regulatory authority for a 17 per cent increase in the price of a basic stamp, bringing it to 48c.
Defending its next-day delivery rate, the company said PriceWaterhouseCoopers had consistently put it close to 90 per cent in independent surveys since 1998.
Performance was 4 per cent lower in the first quarter of this year compared to the same period in 2002 because of temporary difficulties with switching to a new sorting system.
Ms Doyle contrasted An Post's figures with the average next-day delivery rate of 73 per cent in the TNS mrbi survey.
"The clear inference is that bulk mail, some of which is posted at a discounted price, and which is sometimes pre-sorted and in standardised formats, is delivered more rapidly than the ordinary correspondence," she said.
