Britain is enduring a weekend of travel chaos as the start of the summer getaway is disrupted by queues and delays at airports and the Port of Dover.
After bumper-to-bumper traffic on Friday, with six-hour queues on roads leading to Dover, Saturday is expected to be worse.
"This awful situation should have been entirely avoidable and is unacceptable," foreign secretary Liz Truss said. "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. We will be working with the French authorities to find a solution.”
It is one of the busiest periods for foreign travel from the UK as most schools in England and Wales break up for summer.
There were huge crowds at airports including Heathrow and Manchester on Friday morning amid a further spike in demand for summer travel.
Heathrow passengers on Twitter complained about “absurdly long” security queues and called the situation a “shambles”.
Long queues formed outside Bristol Airport in the early hours of the morning.
Drivers waiting to board ferries at the Port of Dover were forced to wait for up to six hours, leading to a “critical incident” being declared by port management.
Dover criticised French authorities for “woefully inadequate” border control staffing.
Natalie Elphicke, Conservative MP for Dover, claimed French border officers “didn’t turn up for work”.
A driver named Ben wrote on Twitter: “4.5 hours in traffic and still 2 miles from Dover Port. Traffic chaos. 4 kids in the car. 'Think of the children'".
Passengers embarking on cross-Channel sailings from Dover must pass through French border checks before they can board a ferry.
The Kent port said in a statement that it has increased the number of border control booths by 50 per cent and shared traffic volume forecasts “in granular detail” with the French authorities.
“Regrettably, the PAF (police aux frontieres) resource has been insufficient and has fallen far short of what is required to ensure a smooth first weekend of the peak summer getaway period,” the port said.
Port chief executive Doug Bannister declared: “We’ve got a critical incident under way.”
He told BBC Radio Kent the port had been “badly let down this morning by the French border”.
“Insufficient resources and much slower than then even normal transactions, which is leading to significant congestion around the port this morning,” he added.
But Pierre-Henri Dumont, MP for Calais, said these problems at the port will reoccur "because of Brexit".
"This is an aftermath of Brexit. We have to run more checks than before," he said.
Mr Dumont also said the Port of Dover was "too small" and there are too few kiosks due to lack of space.
Ms Elphicke said there has been “weeks of preparation” for this week by the port, the Department for Transport and Kent Resilience Forum, and “much work with French counterparts too”.
But she said despite forward planning, French border officers “didn’t turn up for work at the passport controls as needed” and this “caused massive delays.”
“More French officers are reported to be arriving,” she added. “It’s vital that the French passport controls are fully staffed during this peak holiday period.”
Delays at Dover are causing tourist and freight traffic to be stuck on gridlocked roads in the area.