Travellers have booked last-minute Eurostar tickets out of the UK amid flight cancellations, closing international borders and a tightening of Covid-19 restrictions.

A long, snaking line of passengers formed inside St Pancras station in central London on Sunday as they waited to board one of the afternoon’s sold-out Eurostar trains.

One 23-year-old Frenchman, who only gave his name as Francois, said he booked his ticket to Paris in the morning after changing it from next week.

He told the PA news agency: “I know that it’s not really good to leave and go back to France. I haven’t seen my family for four months and a half.

“I tried to isolate myself as much as possible.

“I booked my train this morning, not really reasonable because of the evolution of the virus.

“It’s a pretty personal choice, I don’t feel proud about that.”

The sales management student admitted he was “worried” ahead of seeing his family, adding that he planned to self-isolate and take a test first.

Miguel Gallego, 32, from the Netherlands, said he booked his train ticket “half an hour” before speaking to PA.

Travelling to Brussels in Belgium, he had seen both a flight and Eurostar train to Amsterdam cancelled.

Mr Gallego, who works in aerospace engineering, explained he was moving for work and his house was now empty.

Asked if he had considered staying in the UK, he said: “I would have if I could have a place to stay but at the moment the easiest (thing) is to go away.

“To be honest I wouldn’t know what to do if I didn’t have this train.”

New Tier 4 rules imposed on London and parts of the South East and East of England mean people can only travel out of these areas for limited reasons, such as for work, education or caring responsibilities.

International travel is also restricted to legally permitted reasons, including for work.

Prime Minister Boris Johnson introduced the tougher measures amid concern that a new strain of coronavirus was driving up cases.

Eurostar trains between Belgium and the UK are cancelled from Monday, following the Belgian government’s announcement that borders with the UK will close at midnight on Sunday.

No trains will run between London, Brussels and Amsterdam, but trains continue to operate on the Paris route.

Belgium has also been joined by Italy and the Netherlands in banning flights from the UK.

Amid suggestions France was likely to ban UK travellers, three Eurostar trains leaving London for Paris on Sunday, at 12.24pm, 3.31pm and 7.01pm were sold out on Sunday.

One traveller, who only gave her name as Marie, booked her Eurostar ticket to France a month ago.

Asked if she had thought about not travelling, she said: “No, because I want to go to friends for Christmas so I didn’t want to cancel my ticket.”

She said she planned to take a coronavirus test, explaining: “I’m going to do it when I arrive in France today or tomorrow, it’s pretty quick in France.”

A 21-year-old engineering student travelling home to Brussels, who did not want to be named, said he was heading back for work and to access documents and a working computer.

He said: “I contracted the coronavirus a month ago. I should be pretty immune. I know it’s not 100% sure. I’ve been self-isolating for the last two weeks. Hopefully it’s going to be OK.”

The student criticised the UK Government’s “abrupt” changes to Covid-19 restrictions in England.

“Now they just created chaos and chaos is never good for any reason,” he said.