British Prime Minister Boris Johnson has announced a “stay at home” order for London and southeast England to slow a new coronavirus strain that is significantly more infectious.

Early data suggests the new strain could be “up to 70 per cent more transmissible,” Johnson said at a televised briefing.

He ordered new restrictions for London and south-eastern England from Sunday, saying that “residents in those areas must stay at home” at least until December 30, AFP reported.

The aim of the new rules is to slow the spread of the new strain to areas where it is not yet prevalent. The measures will mean around a third of England's population cannot travel or meet other households for Christmas.