Berlin: Two men have been arrested over a series of arson and threats in Berlin in what investigators believe are far-right motivated crimes, prosecutors in the German capital said Wednesday.

At least 72 cases of arson targeting cars or threats were recorded between 2016 and 2018 in Berlin's Neukoelln district.

The attacks were aimed at left-leaning activists or volunteers helping refugees.

Berlin police "carried out arrest warrants today against two suspects," said prosecutors in a tweet, adding that the operation related to a "series of suspected extreme right motivated violations in Berlin-Neukoelln".

Authorities did not name the two suspects but they were identified as Sebastian T. and Tilo P. by Tagesspiegel daily.

Ferat Kocak, a local politician from the Left party whose car went up in flames at night in 2018, said he was afraid despite the arrests.

"Fear that they will be free again. Fear that they will carry out an act of revenge," he wrote on Twitter.

Europe's biggest economy has been hit by a string of far-right attacks over the last 18 months, leading Interior Minister Seehofer to point to far-right extremism as the "biggest security threat facing Germany".

Among a string of far-right terrorist attacks that have shocked Germany are the assassination of pro-refugee politician Walter Luebcke at his home in June 2019 and the murder in the western city of Hanau of nine people of migrant origin in February.