Hundreds of Eurostar passengers have seen their trains delayed or cancelled due to a technical issue with UK Border Force e-gates.
On Thursday evening, the Home Office said the issue had been resolved, adding that it was working to “fully restore services”.
Eurostar apologised for the delays, saying affected passengers would be offered alternative travel or refunds.
At Paris Gare du Nord earlier in the day, hundreds of people were waiting in huge queues, many of them families with young children on their half-term break.
Eurostar said services in both directions between Paris and London were affected.
E-gates are self-service barriers which automatically read travellers’ passports. Eurostar passengers go through both French and British passport control before getting on the train.
At Gare du Nord, travellers heading to London were told to expect severe delays or last-minute cancellations. About 300 people could be seen standing in the queue to get to the immigration desk at the station.
Waiting in the queue for passport control was Kesha Hancock from Hertfordshire. She was returning to London with her husband Krys and their 10-year-old daughter, Hollie.
She told the BBC that the ordeal had proven a stressful end to the family’s holiday.
“This is the second time we have been to France in two years. The last time was on the ferry and this feels like déjà vu. I can’t help thinking that Brexit is the problem,” she said.
Lizanne O’Connor, from Surrey, described the scene as “slightly chaotic”.
“More information and clarity would be good,” she said, adding that she was travelling with her grandparents and children who had not been offered water.
“They keep repeating the same information.”
Dhruti Cramer, from Ohio in the US, told the BBC that despite the stressful situation most people, including staff, were remaining calm.
“If my children were younger, things would be more difficult.”
Eurostar said: “We advise those who can to postpone their journey. We are offering affected customers exchanges free of charge or a full refund of their journey.”
The Home Office said: “This issue has now been resolved and we are working with European ports and carriers to fully restore services.
“We apologise to all passengers for the inconvenience caused.”
Earlier this month, an issue with Border Force e-gates caused huge delays at several UK airports.
The issue persisted for more than four hours before being fixed.