Boris Johnson today defied a huge Tory backlash to insist coronavirus testing on arrival at airports would only give a 'false sense of security'.

MPs voiced frustration as Mr Johnson again poured cold water on the idea, despite desperate pleas to reform the Government's blanket travel quarantine policy in order to prevent the 'demise' of the aviation sector.

The premier said Public Health England believed only seven per cent of cases could be caught by screening people on arrival. 

Speaking during a visit to a HS2 site in Solihull, he said he understood the 'difficulties' faced by the air industry but the 14 day self isolation requirement remained 'vital'.

A No10 spokesman added: 'Testing at the border does not work to catch people who may go on to get the virus.'

But Conservative MP Henry Smith, who chairs the all-party group on aviation, pointed out that other major countries such as Germany and France were already introducing testing at airports.

He said the government could not allow the UK to be at a 'competitive disadvantage'.  

A growing band of Tory rebels are hoping that airport testing could be the next in a string of government policy U-turns. In a potential chink of light, Grant Shapps today admitted that the move could halve the 14-day quarantine period. 

While he stressed routine screening was not a 'silver bullet', Mr Shapps suggested that it could be a way of reducing the restrictions on travellers from higher-infection countries. 

The comments came as the Cabinet minister conceded that the government's  quarantine rules are causing 'confusion', after England kept Portugal on the safe list - despite Scotland and Wales imposing curbs.

Amid rising anger from bewildered holidaymakers that the system amounts to 'roulette', the he said starkly different approaches within the UK were a problem.

But he insisted that the Westminster government had assessed the best evidence and concluded that Portugal was still low-risk, and swiped at Scotland for decreeing that travellers from Greece must self-isolate this week before even seeing the latest data.