UK plans to introduce a 14-day mandatory quarantine for international arrivals, sparking alarm among airports and airlines already suffering from the coronavirus pandemic, according to the media report on Saturday.

Prime Minister Boris Johnson is expected to unveil the measure on Sunday evening, when he sets out his plans to gradually ease a nationwide stay-at-home order imposed in late March.

He has already signaled that he will proceed with “maximum caution” as the death rate falls only slowly in Britain, the worst hit country in Europe with more than 31,000 confirmed coronavirus deaths.

The Times newspaper reported that anyone coming into Britain by plane, train or boat will be required to self-isolate for a fortnight.

It said the rule would be enforced through spot-checks on the address given by travellers, with possible penalties including fines of up to £1,000 ($1,200, 1,100 euros) or deportation.

The measure would be introduced from the end of May, the BBC reported.

On Wednesday, PM Johnson said that he could begin to ease a nationwide coronavirus lockdown next week, but warned he would do nothing that would risk a new surge of cases.

Speaking in parliament for the first time since he himself was hospitalised with coronavirus, Johnson said the government would review the data and he would set out the next steps on Sunday.

Derek Provan, chief executive of AGS Airports, which owns and operates several regional British airports, said any quarantine must be regularly reviewed.

Airlines UK, the industry association representing UK-registered carriers, had previously warned a quarantine would “effectively kill international travel to and from the UK”.

The country is now the third-most affected in the world behind the United States and Italy on cumulative deaths, after changing its reporting to include community as well as hospital deaths on Wednesday.

Johnson returned to work in Downing Street on Monday but missed Prime Minister’s Questions on Wednesday following the birth of his son.

Britain refused to follow other countries in shutting its borders at the start of the pandemic, saying it would have little effect as coronavirus was already in the country.

Johnson’s government has already warned the public not to expect any big overnight changes to the lockdown this week, although garden centres are expected to be re-opened on Wednesday.

According to the Johns Hopkins database, the UK reported a total of 207,977 confirmed cases of novel coronavirus infection and witnessed 30,689 deaths at one of the highest mortality rates of 14.75 per cent at last count on May 7.