British Prime Minister Boris Johnson has announced the tightening of coronavirus restrictions for London and much of southeast England, citing a fast-spreading new variant of the virus.
Johnson made the announcement at a news conference on Saturday.
Health Secretary Matt Hancock said last Monday that a new variant had been identified, and it could be linked to the rapid spread of the virus in southeast England.
Under the new measures, residents will be asked to stay at home unless they have a specific purpose or a reasonable excuse. All non-essential shops will have to close.
The restrictions are similar to the national lockdown imposed in England last month.
Johnson said the rapid spread appears to be driven by the new variant. He said it may be up to 70 percent more transmissible than the original version, although there is considerable uncertainty.
The prime minister added there is no evidence that suggests the new strain causes more serious illness or weakens the effectiveness of vaccines.
The government had planned to relax coronavirus rules in England for five days from next Wednesday, allowing up to three households to meet for Christmas.
But the plan has now been scrapped for the southeast, and cut to just Christmas Day for other areas.
Johnson said he knows how disappointing the latest step will be, but there is no alternative open to him as prime minister.
Critics said the decision came too late.
Similar restrictions will be imposed from Sunday in Wales, which has also experienced the spread of the new variant.