Holidaymakers and other passengers hoping to cross the channel on Eurotunnel's Le Shuttle service have been facing delays of up to five hours on 25 July, due to disruption by migrants at Calais.
Early on Saturday, Eurotunnel warned of an hour's delay at check-in for passengers taking their vehicles to France, and a further four hours delay before departure.
Shortly after 9am the delays eased, but passengers were still facing an hour-long check-in delay and a further 90 minutes delay before departing.
The company stated that services were suspended for a short period before midnight on 24 July due to "migrant activity" and that the French authorities were dealing with the situation.
Services resumed by 1am on 25 July, but with the ongoing delays.
In another tweet to a passenger hoping to cross after midday, Eurotunnel said: "It's not easy to estimate how long the delays will take to resolve. We're all doing our best," adding, "Please be assured we are operating a full service with four departures per hour and hope to reduce and end delays for our customers."
All scheduled services on 25 July are sold out on Le Shuttle, on a day which is usually one of its busiest of the year.
Around 15,000 passengers are booked on the service, which takes passengers across the channel in cars, caravans, buses, lorries and other vehicles. Normally the service operates runs up to four crossings every hour.
Eurotunnel says that journeys from France to the UK are running on time, with three departures each hour. It will be tweeting travel updates throughout 25 July.
Meanwhile, Operation Stack – which has shut the M20 between junctions 8 and 11, to prevent lorries from congesting roads to the Eurotunnel – continues, with all traffic other than lorries diverted onto the A20.
Around 5,000 migrants are camped in Calais and invasions of the Eurotunnel terminal in Coquelles by migrants are taking place on a nightly basis.
Services were delayed on 23 July when the body of a suspected migrant was discovered on the roof of a Eurotunnel train after it reached Folkestone. The teenager is believed to have died in France.