A blockade by French fishermen has disrupted cross-Channel ferry services.
Fishing boats began stopping ferries from entering or leaving the port of Calais in northern France on Thursday morning.
The port is used by thousands of tourists and hauliers every day to travel to and from the UK.
P&O Ferries said its ship Spirit of Britain was delayed by nearly four-and-a-half hours before it was able to leave Calais for Dover at 12.10pm.
The firm’s chief executive Janette Bell said bringing Calais to a standstill was “utterly unacceptable” and urged the French authorities to ensure the blockade was “cleared without further delay”.
She went on: “I would like to apologise to every one of our customers and assure them that our dedicated employees will be doing everything they possibly can to help them complete their journeys as soon as possible.”
The fishermen are reportedly protesting against electric pulse fishing by other countries.
They claim the method – which involves stunning fish to make them easier to catch – is depleting stocks.
Road Haulage Association chief executive Richard Burnett warned that the impact of the dispute could increase the number of lorries targeted by migrants.
He said: “Our concern is that the ensuing backlog will have turned them into sitting ducks for migrant activity.
“These people, desperate to reach the UK by whatever means possible, must have thought that all their Christmases had come at once.
“We fear greatly for the safety of drivers as lives and livelihoods are put under threat.”
Dover MP Charlie Elphicke said: “This underlines yet again how strikes in France can cause chaos on our roads in Kent.
“President Macron urgently needs to get a grip of the situation and put a stop to the disruption – which is damaging for both the French and British economies.”
He called for greater investment in roads leading to England’s Channel ports and more lorry parking facilities to stop roads becoming clogged up.