Brittany Ferries plans to introduce a new “green” ferry across the Channel in 2019.

The company has signed a letter of intent with the Flensburger Schiffbau shipyard in Germany to built the ship powered by liquid natural gas (LNG).

A final contract for the 1,680-passenger, 257-cabin vessel is expected to be signed in spring 2017, with construction to start shortly afterwards.

The new ferry is expected to enter service in 2019 on the Portsmouth-Caen route, which carries around 70% of the company’s passengers and offers three daily return sailings.

The vessel will operate in tandem with cruise ferry Mont St Michel, which launched in 2002.

Brittany Ferries claims the new addition to the fleet will be one of the cleanest, most environmentally-friendly ships to operate in UK waters.

This is because LNG emits less carbon dioxide during combustion than marine fuel oil and burns with no smoke. In addition it is free of sulphur and is low in nitrogen oxide emissions.

The announcement follows the completion of a £65 million investment in emission-reducing ‘scrubber’ systems which have been retrospectively fitted to six ferries in the company’s ten-ship fleet.

Chief executive Christophe Mathieu said: “The signing of this letter of intent with the Flensburger shipyard is a concrete step towards the construction of a new generation of Brittany Ferries ships.

“Despite Brexit, we remain confident in our ability to continue to grow and modernise our route network, serving both tourism and trade in the regions of western Europe.”

More than four in five people travelling on the French company’s ships are British and more than 2.4 million passengers were carried in 2016.