The head of Germany’s public health agency has said he is “very concerned” by rising infections in the country.
“We are in the middle of a rapidly developing pandemic,” Lothar Wieler, head of the Robert Koch Institute (RKI), told reporters.
Mr Wieler said Germans had become “negligent” and urged people to wear masks and respect social distancing and hygiene rules.
In the past week the country has recorded 3,611 new infections.
The warning comes as countries across Europe grapple with new infections and the problem of travellers moving across the continent for the summer holidays.
On Tuesday Germany issued a travel warning for three regions in Spain – Aragón, Catalonia and Navarra – which have seen a recent spike in infections.
It comes after the UK imposed a 14-day quarantine on all arrivals from Spain – a move Spanish Prime Minister Pedro Sánchez called “unjust”.
Germany announced on Monday a programme of free, mandatory coronavirus testing for travellers returning from a list of high-risk countries. The list currently includes Brazil, Turkey and the US, and officials said it will be updated daily.
What did Mr Wieler say?
At a press conference on Tuesday, Mr Wieler asked people for the first time to wear a mask outdoors if they cannot maintain a physical distance of at least 1.5 metres (5ft).
Previously the guidance had been to wear masks indoors in public.
The head of the RKI said Germans must stop the virus once again spreading “rapidly and uncontrollably” by following hygiene and distancing measures.
“We don’t know yet if this is the beginning of a second wave but of course it could be,” Mr Wieler said. “But I am optimistic that if we follow the hygiene rules we can prevent it, it’s up to us.”
How is the virus spreading in Germany?
Overall, Germany has recorded 206,242 cases and 9,122 deaths.
These numbers – in particular the death toll – are lower than many other European states, and Germany has won praise domestically and internationally for its rapid response to the pandemic and its mass testing programme.