Sri Lankans were among 33 people injured after a bus travelling from Paris to London overturned in northern France.
Four people were seriously injured and 29 others wounded when the FlixBus coach toppled at an exit near Amiens on the A1 motorway on Sunday morning.
Northern Ireland couple Jamie Kerr and Gemma Given, both 20, were treated in hospital for head and hand injuries.
Eight other Britons were on board, alongside passengers from nine nations.
The coach was also carrying 11 people from France, five from the US, two from Romania, and one each from Spain, Australia, Mauritius, Japan and Sri Lanka. They were taken to local hospitals.
Police had previously said there were 11 people from the UK on the coach.
The Foreign Office said three Britons remained in hospital.
Jamie's father John Kerr told BBC News: "It was a pretty traumatic end to a Halloween weekend."
His son, a student at Glasgow University, had called on Sunday morning to say he and his girlfriend, Ms Given, were involved in the crash, which took place at around 11:00 GMT, but were not badly injured.
It is understood Ms Given, a student at Brighton University, had her bag taken for examination by police because a passenger who was seriously injured had been lying on it.
"That brought home to me how close they were to being seriously injured," said John Kerr.
He said the couple were offered a bus back to the UK but said they would make their own way home.
"I feel a bit more could have been done for them," he said.
"They'll learn a lot from all of this but I'm expecting an emotional response when they get home and it all hits them."
The Foreign Office said it was in contact with French authorities. "We will do all we can to assist any British people who need our help," a spokeswoman said.
The British embassy in France confirmed British nationals were involved in the incident.
Local police tweeted they had sent all state services to the scene, while firefighters urged motorists to avoid the area.
In a statement, FlixBus said there were 32 passengers and one bus driver on board.
A spokesman said: "FlixBus is in close contact with the relevant authorities in order to determine the exact cause of the accident and to ensure all passengers receive appropriate support.
"An emergency phone number is available for the passengers and their relatives."
Those concerned about loved ones are asked to call 0080030013730.
Last month, another FlixBus coach crashed near Narbonne, in south-west France, killing one person and injuring several others, according to local media. (BBC)