UK, Germany and Italy detected cases of the new Omicron coronavirus variant on Saturday and British Prime Minister Boris Johnson announced new steps to contain the virus, while more nations imposed restrictions on travel from southern Africa.

The discovery of the variant has sparked global concern, a wave of travel bans or curbs and a sell-off on financial markets on Friday as investors worried that Omicron could stall a global recovery from the nearly two-year pandemic.

The two linked cases of Omicron detected in Britain were connected to travel to southern Africa, British health minister Sajid Javid said.

Johnson laid out measures that included stricter testing rules for people arriving in the country but that stopped short of curbs on social activity other than requiring mask wearing in some settings.

“We will require anyone who enters the UK to take a PCR test by the end of the second day after their arrival and to self-isolate until they have a negative result,” Johnson told a news conference.