Germany's health authority announced late Saturday that Britain has been added to its list of COVID-19 high-risk countries, which will mean tighter travel restrictions. 

The decision is a response to the rapid spread of the Omicron variant, which forced London's mayor Sadiq Khan to declare a "major incident" on Saturday in the British capital. 

The change, which takes effect at the end of the day Sunday at midnight, means arrivals from Britain will have to observe a two-week quarantine regardless of whether they are vaccinated, said the country's health agency, the Robert Koch Institute (RKI).