Eurotunnel has warned passengers who have booked to take their vehicles across channel face long delays of around three hours after "migrant activity" in Calais caused the brief suspension of services last night.
"Our passenger service is currently operating with some timetable disruption, this is due to an earlier incident in the terminal which has now been resolved," it said.
"There is a waiting time of approximately 60 minutes before check in and 2 hours on the terminal. We regret that we are are currently unable to sell tickets to non reserved customers."
The first Eurostar service departed on time at 6.18am this morning, with all other services running on time, according to its website.
Operation Stack, in which lorries bound for France queue on the M20 when cross-Channel services are disrupted, is also in place.
Customers arriving late due to traffic problems will be given the next train with space be aware there's a 4 hour delay at present in UK ^CM— Eurotunnel LeShuttle (@LeShuttle) July 25, 2015
Overnight migrant activity in Calais caused us to suspend our service We have now resumed service but it will take time to reduce delays ^CM— Eurotunnel LeShuttle (@LeShuttle) July 25, 2015
Passenger service from UK currently has a wait of 2 hours on site and a further 1 hour at Check in. We are working to reduce this delay ^CM— Eurotunnel LeShuttle (@LeShuttle) July 25, 2015