Eurostar has been forced to run trains with a large number of empty seats between London and its destinations in Europe, in order to prevent backups at border checkpoints at its stations.

The cross-channel train operator, which is controlled by France’s state-owned SNCF rail system, said that Brexit and a shortage of border officials was increasing the time it takes to process passengers departing from London’s St. Pancras International station, the Press Association reported, citing Eurostar Chief Executive Officer Gwendoline Cazenave. 

As a result, some services are running with as many as 30% of their seats empty, Cazenave said. 

Eurostar has seen a surge in demand as travel rebounds after the pandemic, and the operator is trying to convert air travelers seeking greener alternatives. Following a previously announced merger with the Thalys rail service that operates between Paris and Brussels, all services operated by the merged entity will be rebranded under the Eurostar banner with the operator touting more seamless connections between London and continental Europe.