The right-wing populist Alternative for Germany (AfD) party clinched almost 21 percent in its first bid for seats in the regional parliament of Mecklenburg-Western Pomerania on Sunday.

With her eyes on national elections next year, AfD co-chief Beatrix von Storch hailed the shock outcome as "the beginning of the end of the Merkel era", while Bild daily labelled the result another "slap across the face" for the chancellor.

The AfD's rise mirrors success enjoyed by other anti-immigration parties across Europe, with France's Front National (FN) riding high in the polls and a far-right populist eyeing the presidency in Austria in elections on October 2.

Merkel's conservative Christian Democratic Union (CDU) won just 19 percent in its worst ever score in the ex-communist northeastern state, while the Social Democrats maintained top place with over 30 percent.

The state vote was held exactly one year after Merkel opened German borders to a mass influx of Syrian refugees and other migrants that would swell arrivals in Europe's top economy to one million asylum seekers in 2015.