Holyhead port 'would be most affected' by Brexit hard border
Drivers will face long delays at ports and tailbacks on the roads if Brexit is not handled properly, an assembly committee has warned.
Its report said urgent action was needed to avoid disruption.
AMs on the cross-party external affairs committee also said they were disappointed by how little contact there had been between the Welsh and Irish governments to discuss Brexit.
The Welsh Government said it would look at the report and respond formally.
Dr Andrew Potter, lecturer in transport and logistics at Cardiff University, said Holyhead, Wales' busiest port which handles about 350,000 trucks a year, would be most affected.
"If there's a soft border between the Republic of Ireland and Northern Ireland but a hard border across this maritime link, it may the affect competitiveness of Welsh ports as traffic will divert to English or Scottish ports," he said.
