Germany's list of "risk zones" currently includes most non-EU countries, as well as certain provinces in Belgium and Spain.
Neighbouring Austria on Thursday announced it would issue a travel warning for mainland Spain, becoming the latest country to do so amid a rise in new coronavirus cases in the fellow EU member.
Finland also introduced new controls on arrivals from some EU countries, including Belgium, the Netherlands and Andorra, putting a stop to tourists arriving from there and imposing a 14-day quarantine on other returnees.
"The situation is extremely delicate," the health ministry's strategic director Liisa-Maria Voipio-Pulkki said, adding that "some sort of second stage has begun."
"Whether we can expect a smaller wave or a larger wave depends on how we respond."
Britain has reimposed quarantine for travelers from Belgium, Andorra and Bahamas.
Norway announced Thursday that France would be considered a red zone due to the resurgence of coronavirus cases there, meaning all travellers arriving from France face a mandatory ten-day quarantine.
Switzerland, Monaco and the Czech Republic were also hit with similar restrictions, as well as two Swedish regions, the Norwegian foreign affairs ministry said.
"The infectious situation can change quickly, as can the restrictions," Foreign Minister Ine Eriksen Soreide said in a communique.
The United States on Thursday bucked the trend despite its own soaring death toll, lifting a blanket warning against all foreign travel.
"Health and safety conditions (are) improving in some countries and potentially deteriorating in others," the State Department said in a statement.
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Many nations are seeing new outbreaks, forcing local or citywide lockdowns and other quarantine measures.
Poland will re-impose compulsory face masks in all public spaces in nine districts, the health minister said, as it saw a record new high in the number of infections.
The restrictions will come into force from Saturday and will also affect sports and cultural events in those areas, mainly in the south and east.
Greece's government on Wednesday announced a "wake-up week" on COVID-19, tightening restrictions after the steady rise in mostly domestic infections.
Officials have blamed the increase on overcrowding in clubs and social events.
Trends in the number of daily coronavirus-related cases and deaths in selected European countries AFP/Simon MALFATTO
The new virus outbreaks are forcing officials into an uncomfortable trade-off between health requirements and the need to bring economies back to life as businesses and companies struggle.
German airline Lufthansa on Thursday became the latest to reveal the fallout from the pandemic, announcing forced layoffs and a 1.5 billion euro (US$1.7 billion) loss in the second quarter.
Announcing its worst quarter in the company's history, Lufthansa said in the three months to June its passenger numbers had collapsed by 96 per cent compared to last year.