Eurostar passengers departing from London can avoid manual checks of tickets and passports by UK officials through a facial verification system.
The launch of the technology at St Pancras station is aimed at easing congestion.
To participate, passengers must use an app before travel to scan their identity document and verify their face and ticket.
At the station they walk in front of a screen and have their face detected.
If they are approved they can proceed through doors which open automatically.
The SmartCheck system, developed by iProov, is available to Business Premier and Carte Blanche passengers.
Bags are still being scanned by security staff and French border officials are continuing to 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.
Enhanced post-Brexit checks carried out by French border officials have significantly increased the time it takes to process passengers at the station.
Eurostar chief executive Gwendoline Cazenave said: “Providing a seamless station experience to our customers is a priority for Eurostar.
“We continue looking for solutions to increase capacity in stations and simplify the passengers’ flows.
“SmartCheck in St Pancras International station is a solution for a faster and seamless check-in experience.
“By introducing SmartCheck, we become the first rail travel operator to adopt biometric face verification.
“This innovation will enhance our customer departure journey, which is crucial to provide Eurostar’s unique travel experience.”
Andrew Bud, chief executive of iProov, said: “The rollout of SmartCheck in Eurostar’s Business Premier check-in at London St Pancras is significant because it clearly demonstrates how facial biometric technology can be used to manage border control in a smarter and more efficient way, to benefit both organisations and passengers at scale.
“By creating a biometric corridor, we are moving security checks away from the station, saving precious time and space at the border, streamlining the boarding process to one that’s far faster, more convenient, less crowded and stressful, yet even more secure.”
Heathrow Airport began trialling facial biometric scanners in 2019 but the project was dropped when passenger numbers collapsed due to the coronavirus pandemic.
