Some Eurostar passengers travelling from London can now avoid manual ticket and passport checks by UK officials due to a new facial verification system.
The technology at St Pancras International station is aimed at reducing congestion and queues.
Enhanced post-Brexit checks by French border staff have increased the time it takes to process passengers at the station, the company said.
Business Premier and Carte Blanche passengers can use the system.
Passengers will need to use an app before travel to scan their identity document and verify their face and ticket.
Eurostar said it would like to make the new technology – a first for UK rail travel – available to more customers in future, if it proves successful.
Heathrow Airport began trialling facial biometric scanners in 2019 but the project was dropped when passenger numbers collapsed due to the coronavirus pandemic.
The company also said that while the system, called SmartCheck, is only in use at St Pancras, it could be introduced more widely across the Eurostar network in mainland Europe.
The firm’s chief executive Gwendoline Cazenave said: “We continue looking for solutions to increase capacity in stations and simplify the passengers’ flows.
Bags will still be scanned by security staff and French border officials will also check passports.
It emerged earlier this year that Eurostar was being forced to leave hundreds of seats empty on trains to and from London to avoid long queues at stations.
The situation has since improved but dozens of seats are not being offered for sale on some services.