German Chancellor Angela Merkel denounced the deadly shooting rampage at a synagogue in the US city of Pittsburgh on Saturday as "blind anti-Semitic hatred".

"We all have to stand up against anti-Semitism, everywhere," she said, in a brief statement posted on Twitter by a German government spokesman. Eleven people were killed and six injured in the shooting, the city's public safety director Wendell Hissrich said, an attack the FBI is investigating as a federal hate crime.