Armed guards could be based on cross-Channel ferries after talks between France and the UK over tighter maritime security.
Officials in both countries are working on proposals that would allow sea marshals to board ferries in French ports and remain on the vessels as they cross the Channel, The Times reported.
British maritime officials have asked the French to provide an appraisal of the security situation and set out how the plain-clothed officers would operate.
The French government approached the British with the idea as part of measures to bolster security across the country after the terror attacks in Paris, Nice and Rouen.
Brittany Ferries carried out an exercise this week with guards aboard the ferry Mont St Michel, travelling from Portsmouth to Caen, as part of moves to integrate the highly-trained military personnel into the security network.
French marine police spokesman Lieutenant Pierre-Joachim Antona told the AFR news agency that a “permanent unit” had been deployed since Monday to carry out high-visibility patrols on passenger ferries.
“The marine gendarmes will carry out patrols, which will be random but regular, with the aim of securing these vessels against the terrorist threat,” he said.
The first patrol took place on Monday, when three French sea marshals arrived on the Brittany Ferries vessel by helicopter.
A Brittany Ferries spokesman said the vessel left Portsmouth for Caen in France at 2.45pm and, in a “pre-scheduled security exercise”, the marshals were flown on to the ferry at 5.30pm.
“They then proceeded to patrol the bridge and passenger areas of the vessel,” he told the BBC. “Passengers were informed via announcements in English and French before the exercise took place. Access to outside decks was not allowed at the time of the helicopter’s arrival.”
A permanent unit allowing patrols to be flown on to ferries in French and international waters has been operational since the beginning of the month.
France wants to expand the operation to enable guards to be permanently on French-flagged vessels as they travel across the Channel and into British ports. They would not be on ferries operating under a UK flag.