The offices of a German newspaper have been daubed with neo-Nazi graffiti and anti-Semitic messages of hate because of its coverage of far-right groups.

The words "Jews" and the Nazi slogan "Sieg Heil" were spray-painted onto the office windows of the Lausitzer Rundschau newspaper. The week before, four swastikas were drawn onto the windows as well as the messages "Jews, kill them" and "We'll get you all".

The Organisation for Security and Cooperation in Europe condemned the attacks on the East German newspaper as "unacceptable and must be stopped".

"These threats and acts of vandalism must be stopped and I am confident that the authorities will take the necessary precautions to ensure journalists' safety," the OSCE's media representative Dunja Mijatovic said.

"I welcome the condemnation of these attacks from the highest level of the German authorities in Brandenburg state and trust that these incidents will be swiftly and thoroughly investigated," she said in a statement.

The newspaper faced similar incidents in 2012. Johannes Fischer, the editor of the newspaper, said that the publication would fight back against the attacks with words - "the most powerful weapons against spray cans and baseball bats".

The attacks came before German Chancellor Angela Merkel addressed a rally in Berlin vowing to increase efforts to combat anti-Semitism.

"It pains me when I hear that young Jewish parents ask whether they should raise their children in Germany, or elderly Jews who ask if it was right to stay," she said.

"With this rally, we are making it unmistakably clear: Jewish life belongs to us. It is part of our identity and culture."

"The legitimate criticism of the political actions of a government — be it ours or of the state of Israel's — is fine," Merkel continued.

"But if it is only used as a cloak for one's hatred against other people, hatred for Jewish people, then it is a misuse of our basic rights of freedom of opinion and assembly."

Germany has a population of approximately 200,000 Jews.