Berlin's zoo closed its doors without warning on Friday out of precaution after a case of avian flu was discovered in a wading bird that died earlier this week, it said in a statement.
The zoo, which welcomed over 3.7 million guests in 2019, its latest figure, did not mention when it would reopen to visitors.
"We have reacted immediately with far-reaching quarantine measures. Almost all birds - including our penguins - have now been moved to rear aviaries or stables," said Christian Kern, the zoological director of the zoo in Berlin's centre as well as the Tierpark zoo in the eastern part of the German capital.
