An Post has sealed a large number of post boxes in the Drogheda area in what the company says is an effort to reduce pressure on its sorting services.
The action was taken yesterday as a result of what a spokesperson for the company referred to as an "unofficial industrial action" on the part of postal workers in the town.
Speaking to ireland.comthis afternoon, An Post spokesperson Ms Anna McHugh said the company had to take the "drastic action" of sealing post boxes in Drogheda and the surrounding area after a driver could not be replaced when he reported sick for work.
She said over 30,000 items had built up over the last two days and that the company had "no option" but to seal the post boxes in an effort to minimize backlog from building up.
Referring to the refusal to replace the driver as "disgraceful", Ms McHugh said the action "contravened every agreement."
Meanwhile, An Post has said some of its customers in Tuam, Co Galway, had not received their mail due to another dispute, also involving alleged unofficial industrial action.
The Tuam dispute is thought to be over the premises in the town.
Ms McHugh claimed workers had not completed their deliveries recently and that as a result the company had to make special arrangements for the collection of mail.
However, Mr Seán MacDonagh of the Communications Workers Union said there was no industrial action taking place in Tuam, "unofficial or otherwise".
He said a demonstration held over the quality of accommodation at the post office in Tuam last week might have led to a backlog in mail.
But Mr McDonagh told ireland.comthis afternoon that workers were making themselves available for work as normal.
In Galway city, another action by workers meant that up to 15,000 letters and parcels were not sorted today.