Concern over Portsmouth port's HGV Brexit 'border-readiness'
Three out of four lorries are predicted to turn up at Portsmouth ferry port without the right documentation in the wake of a no-deal Brexit.
Customs documents needed by lorries crossing the English Channel will change in the event of a no-deal.
Department for Transport (DfT) analysis suggests 75% will not be "border ready" and will be turned away.
Hampshire and Isle of Wight's Local Resilience Forum has written to the government to express concerns.
In a letter to the Secretary of State, the group described the impact of a lack of "border-readiness" by HGVs arriving at the port to sail to France or Spain as a "major challenge".
The letter adds, "we believe our contingencies may quickly become overwhelmed".
To tackle queues in the event of a no-deal Brexit, a temporary site has been built nearby to hold the lorries.
About 30 miles away the A31 between Alresford and Winchester could also be closed westbound to park lorries.
Brittany Ferries has questioned the figure and said it expected a near-normal service at Portsmouth after Brexit.
Nigel Wonnacott, from the ferry firm, said: "I think we'd be crystal ball gazing at this stage if we were to say for certain everything will be working as normal.
"I would hope with the preparations we've put in place that things will be as near as damn it to how they are today."
The ferry firm added that "understandably" bookings for the first week of November were "down slightly".
A DfT spokesperson said: "If hauliers have the correct documentation, disruption at the border should be limited."
Currently it takes two minutes for each lorry to pass through the check-in gate with up to 60 lorries able to pass through each hour.