As coronavirus cases continue to increase in the Czech Republic, the German government on Wednesday evening declared Prague a “risk area” and warned against traveling there.

Everyone who comes to Germany from Prague is obliged to undergo a 14-day quarantine, or to prove himself with a negative test, which should not be performed earlier than 48 hours before entering Germany.

“We warn against urgent and tourist trips to Prague due to the higher number of cases,” states the official website of the German Ministry of Foreign Affairs. The Ministry also mentions several regions, including Karlovy Vary, Pilsen, Central and Southern Bohemia, where the epidemic situation has been deteriorating sharply in recent days.

The announcement will likely hurt the city’s tourism operators. Hundreds of tourist guides demonstrated outside the city’s town hall, bemoaning lost earnings which are a threat to their existence.

Read: Czech Rep. Reports Over 1,000 Coronavirus Cases for Second Straight Day

“The borders to Germany remain open, but random police checks are taking place,” the Czech Foreign Ministry said in a statement on Wednesday.

Germany also issued a travel warning to the Swiss city of Geneva and Vaud district, as well as the Pozega-Slavonia and Dubrovnik-Neretva regions of Croatia.

The French Ile-de-France, Provence-Alpes-Cote-d’Azur, Auvergne-Rhone-Alps, Occitanie and Nouvelle-Aquitaine regions were added to the list, as was the island of Corsica.

Earlier, the Czech Republic reported its highest rise in coronavirus cases in 24 hours, with 1,164 new infections, according to the Health Ministry.

The World Health Organization on Tuesday described the latest jump in cases in the country as “alarming.”

Read: WHO Czech Republic: “The Covid Situation in the Country is Worrying”

Face masks have meanwhile become mandatory on public transport, and in the capital, Prague, they’re required in stores and shopping centres.

However, according to epidemiologist Roman Prymula, the effects of those measures will become apparent only after a few weeks. “We must work to prevent an exponential increase,” the expert told the Pravo newspaper.