Transport Secretary Grant Shapps has defended plans for prison sentences of up to 10 years for returning travellers who try to evade strict coronavirus quarantine rules.
Ministers have faced accusations that the penalties for UK nationals returning from high-risk destinations who lie about their movements are “disproportionate”.
But Mr Shapps said “strong action” was necessary to prevent new mutations of the virus entering the country, potentially undermining the vaccination programme.
On Tuesday, Health Secretary Matt Hancock announced people returning to England from 33 “red list” destinations would have to pay £1,750 to quarantine for 10 days in Government-designated hotels.
Those caught lying about their movements could be fined £10,000 or jailed for 10 years.
Former Supreme Court justice Lord Sumption said the penalties were more severe than those for some violent or sexual offences.
“Does Mr Hancock really think that non-disclosure of a visit to Portugal is worse than the large number of violent firearms offences or sexual offences involving minors, for which the maximum is seven years?” he wrote in the Daily Telegraph.
Former Conservative attorney general Dominic Grieve said 10-year jail terms were a “mistake” which would never actually be used by the courts.
“This is a regulatory offence, and no regulatory offence I can think of attracts a 10-year sentence,” he told the BBC Radio 4 Today programme.
“The reality is that nobody would get such a sentence anyway, the courts are simply not going to impose it.
“It’s a mistake of the Government to suggest something which is not going to happen.”
However, Mr Shapps said the public would expect strong action if lives were being put at risk by people bringing dangerous new variants into the country.
“I do think it is serious if people put others in danger by deliberately misleading and saying that you weren’t in Brazil or South Africa, or one of the red list countries,” he told BBC Breakfast.
“I think the British public would expect pretty strong action because we’re not talking now just about, ‘Oh there’s a lot of coronavirus in that country and you might bring some more of it back when we already have plenty of it here’.
“What we’re talking about now are the mutations, the variants, and that is a different matter, because we don’t want to be in a situation where we later on discover that there’s a problem with vaccines.”
In the Commons on Tuesday, Mr Hancock indicated the quarantine measures might be in place until the autumn if vaccine booster jabs are needed in response to coronavirus variants.
He told MPs that 16 hotels have been contracted to provide 4,600 rooms for the quarantine programme, which begins on Monday.
The Scottish Government said that it would go further and require all international travellers arriving into Scotland to stay in a quarantine hotel.
No international flights are currently operating to Wales or Northern Ireland, but Stormont’s chief medical officer Dr Michael McBride said it is “crucially important” for the nations to work together to stall the arrival of new and concerning strains from abroad.
Travel trade organisation Abta said requiring passengers to pay for multiple tests once leisure travel is restarted would have “serious cost implications” and “hurt demand”.
A spokeswoman urged ministers to “develop a roadmap to reopen travel”.
Meanwhile, the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) added a new strain detected in Bristol to its “variant of concern” list.
A strain identified in Liverpool has also been classed as a “variant under investigation”.
Public Health England’s Dr Susan Hopkins said the relatively slow rise in cases of the South African and Bristol variant was “reassuring”.
But she warned that controlling them will become much more challenging as lockdown is relaxed.
Health officials said they had so far found 76 cases of the Bristol and Liverpool variants in the UK.
Both those variants contain the E484K mutation, a genetic change also found in both the South African and Brazilian variants, which experts suggest may be better at evading the human immune response.
The Department of Health and Social Care also said extra coronavirus testing was being carried out in the borough of Lambeth, south London, after a case of the South African variant was discovered there.