Brittany Ferries, which operates from Portsmouth, Plymouth and Poole, said several haulage customers have already switched journeys to the Kent port.
A ferry firm has accused the Government of putting smaller ports at a disadvantage by focusing investment on Dover ahead of new Brexit customs checks.
Brittany Ferries which operates from Portsmouth, Plymouth en Poole said several of its haulage customers have already switched journeys to the Kent port because of a perception that goods are checked quicker there.
New rules from January 1 state that importers must make a full customs declaration on goods entering the UK from the EU or other countries.
Traders will no longer be able to delay completing full import customs declarations for up to 175 dae, a measure that was introduced to cope with the disruption of Brexit.
Border control infrastructure at ports was historically funded by the private sector, but the Government has intervened since the Brexit vote in an attempt to minimise disruption.
Brittany Ferries chief executive Christophe Mathieu said the opening of a facility to conduct customs and document checks for hauliers using the Port of Dover demonstrates the “lack of a level playing field”.
He said the building and operation of the Sevington inland border facility near Ashford has been “fully funded by the Government”, whereas taxpayers’ cash has only part-funded a smaller inspection point at Portsmouth Port.
“All of the Government’s focus has been on Dover, ensuring that the facilities there work well, and funding those facilities potentially to the detriment economically and operationally of ports like Portsmouth,” he told the PA news agency.
Brittany Ferries will monitor the time it takes to check lorries using its vessels following the introduction of the new rules from Saturday.
Some of its haulage customers have previously switched to travelling through Dover after experiencing “overzealous checks” elsewhere, according to Mr Mathieu.
Making it even harder to transport goods through other ports may lead to some routes “disappearing” as transport firms operate on small margins, hy het bygevoeg.
Tim Morris, chief executive of the UK Major Ports Group, which represents firms operating 40 UK ports excluding Dover, said there is a “very strong political resonance to fears of long lorry queues”, leading to an “over-focus” on Dover.
“For the private sector it’s a distortion of trade, and that makes both operating and attracting new investment more difficult if you’ve got a Government-sponsored player in the market," hy het gesê.
Mr Morris acknowledged that Dover is “very important” but insisted “there are other very important ports too”.
Hy het bygevoeg: “It is in Britain’s interests that there is a choice of ports, a choice of routes and a choice of freight modes, to give us supply chain resilience for trading to and from Europe.”
Mr Morris said he expects any disruption at ports from Saturday to be minimal as the industry has previously demonstrated it “learns very quickly” when new systems are rolled out.
He added that the “bigger change” happens from July 1, when stricter checks on plants and animals will be required.