Eurostar passengers are facing long delays after a power failure resulted in train cancellations on the busiest day of the Easter getaway.
Frustrated passengers took to social media to complain of "mayhem" and "chaos" at London St Pancras as they awaited information.
Images posted on Twitter showed long queues stretching across the station.
Ben Crosland tweeted: "Total chaos from @Eurostar UK at St Pancras. Held in a pen and nobody knows what's going on. Useless!"
Neil Kendrick wrote: "Queued for 3.5 hours to be told we are on the 6:00 train and given £2 for my patience."
Another posted: "The situation at St Pancras is crazy with a cancelled train to Paris, thousand people waiting and angry guys because the boarding takes time."
A Eurostar spokeswoman said an earlier power failure had caused two train cancellations - one from Paris and one from London.
"The passengers on those trains are being accommodated on other services or they can opt to exchange their ticket", she said.
She added that speed restrictions around Paris were causing further delays.
But she stressed it was "the busiest day of Easter" for Eurostar and said delays had reduced gradually throughout the day.