DPD says it is temporarily 'pausing' deliveries from the UK to Ireland due to Brexit.
The delivery service says there is "extra pressure on our turnaround and transit times".
The pause will be as "short as possible" - with the firm hoping to resume deliveries next Wednesday.
In a statement, the firm said: "We are seeing up to 20% of parcels having incorrect or incomplete data attached, these will have to be returned to you so that the required data can be provided.
"In addition to this we are seeing delays and congestion at UK ports and more rigid requirements for channel crossings.
In view of this unprecedented set of circumstances we believe that it is only right to pause and review our road service into Europe, including the Republic of Ireland.
"We will use this short pause to validate the data we have in our system, reduce the delay and give you the opportunity to give us the correct data we need in order that we can export, from next week, successfully."
It comes as consumers face new charges and taxes when shopping online from the UK due to Brexit.
