Dutch railway operator Netherlands Railways (NS) said the move would increase total seat capacity to a level comparable with 20 to 25 flights. Each Eurostar train has capacity for 900 passengers.

While services between London and Amsterdam run direct, passengers have long had to return via Brussels for security and immigration checks.

However, new timetables that came into effect at the weekend will allow these checks to take place at Dutch Eurostar stations – Amsterdam Central and Rotterdam Central.

This is expected to cut the journey time between Amsterdam and London from five hours to four, and from Rotterdam to three hours 15 minutes in the spring, pending a new treaty involving the UK, France, Belgium and the Netherlands

Now, NS wants to increase the current three daily Eurostar services between London and Amsterdam, via Rotterdam, to four next year and five in 2021, and believes if the expansion is a success, more services could be added “in the long term”.

Heiko Luiten, director of NS International, said: “In a period where there is a lot about the Brexit, it feels extra special to be able to announce more direct trains to London.

“Moreover, international trains are indispensable for making mobility more sustainable, another important task for which Europe faces.

“A train traveller between Amsterdam and London emits 80% less CO2 than someone who will fly. More than 1.6 million travellers per year will soon have the choice between the train or the plane.”

Eurostar is planning to merge with European rail operator Thalys to create a green rail network spanning five countries with the addition of Germany.

The proposed partners say the move is motivated by the challenges posed by climate change and increasing demand for sustainable travel options in Europe.

Eurostar recently marked its 25th anniversary, and will launch a new trade booking portal in spring.