Most people arriving in Britain, by plane, train, road or sea from Monday will have to self-isolate for two weeks under a new coronavirus restriction and must provide details of their journey and the address where they will self-isolate.

The measure applies to both residents and visitors with some exceptions, including for lorry drivers, "essential" healthcare workers and people travelling from Ireland who have been there for at least two weeks. 

But critics question why Britain, where the number of new COVID-19 infections per 100,000 people in the past fortnight was the second-highest in Europe, is inflicting more pain on hotels and airlines by reducing travel from countries with fewer virus cases.

British Airways and budget carriers EasyJet and Ryanair have launched joint legal proceedings against the government over what they called a "disproportionate and unfair" step.

Health Secretary Matt Hancock said the new rules made sense because "the proportion of infections that come from abroad increases" as Britain's own caseload drops.

"We've got to take an approach that starts with caution," he told Sky News.

How the quarantine will be implemented differs between Britain's devolved nations, and the measures will be assessed every three weeks.

Those arriving in England and Northern Ireland could face a fine of 1,000 pounds if they fail to follow the rules, while they would face a 480 pounds fine in Scotland. The maximum fine for repeat offenders in Scotland is 5,000 pounds. The enforcement rules in Wales are not clear.

Home Secretary Priti Patel told skeptical lawmakers in parliament last week that the measure was "backed by the science, supported by the public, and essential to save lives."

The government is pushing ahead with a gradual lockdown easing that will see the retail sector reopen on June 15, and restaurants and bars begin limited service in early July.

But the devastated hospitality sector relies heavily on tourists, and business leaders fear the quarantine will mean much of the summer season will be lost.

It comes after heavily-hit Italy reopened its borders last week and other European states follow suit.

British Prime Minister Boris Johnson's government is trying to arrange "travel corridors" with countries such as France and Spain that could see them lift their quarantine demands.

But officials are reportedly giving themselves until late June to strike these deals, and the airlines behind the lawsuit say they cannot wait that long.

These measures were disproportionate and unfair on British citizens as well as international visitors arriving in the UK, the airlines said in a joint statement.

The quarantine would have a devastating effect on the UK's tourism industry and would destroy thousands of jobs in this unprecedented crisis, they said.

Britain's official death toll of 40,542 trails only that of the United States.

(With input from agencies)