Britain's main gateway to Europe - Port Dover, on Friday (July 22) declared a 'critical incident' as travelers faced hours-long wait, blaming the lack of French customs officials for causing a bottleneck as vacationers left for summer breaks.
The UK's departure from the EU means passengers bound for France now face enhanced checks by French officials.
The cruise port has increased customs booths in order to accelerate the process but it said they were understaffed, leading to gridlock in Dover UK during what is one of the busiest periods of travel.
According to a local French police body, delays had been caused by an "unexpected technical incident" at the Channel Tunnel, without elaborating.
Later, the French embassy in London tweeted that all border checks were "operating at full capacity."
UK's foreign secretary Liz Truss, who is competing to become the next prime minister, said that the "awful situation" was unacceptable.
"We need action from France to build up capacity at the border to limit any further disruption for British tourists and to ensure this appalling situation is avoided in future."
The major delays at Port Dover come as airports also struggle to recruit enough staff to manage the post-COVID rebound in travel, leading to chaos at London airports.
A spokeswoman for the Port of Dover revealed CEO Doug Bannister had declared the situation a 'critical incident'.