Merkel and other German politicians have also looked with worry to neighboring Austria, where the nominally-centrist new Chancellor Sebastian Kurz has formed a coalition government with the ring-wing populist Freedom Party in Vienna.

Despite emphasizing his pro-European credentials, Kurz struck a decidedly-illiberal pose on immigration by vowing to slash government benefits for foreigners in Austria during his successful campaign.

Merkel is reportedly concerned that politicians in other European countries could seek to emulate Kurz' example, unleashing a populist wave on the continent.

Further highlighting the increasing confidence of political forces which are openly xenophobic in the German public sphere, the far-right "Identitarian Movement" attempted to install plaques commemorating "the victims of Islamist terror" at Berlin's landmark Brandenburg Gate where the official memorial service was being held.

The movement claimed responsibility for the plaques on social media which they said constituted a "European memorial for the victims of multiculturalism and Islamist terrorism".

Berlin police subsequently removed the plaques a few hours after they were installed.