Alternative for Germany's dominant showing in Sunday's Saxony-Anhalt election has triggered starkly divided reactions across the continent, exposing the widening fault line between Europe's establishment centre and its emboldened populist right.

AfD won 43.8% of the vote, more than double its showing five years ago in the region of 2.1 million people west of Berlin.

That was far ahead of Merz’s Christian Democratic Union, which polled 17.2% — losing about half its support — and won 15 seats. The center-left Social Democrats polled 9.3%, the Greens 8.9% and the Left Party 8.6%, winning eight seats apiece.

In Berlin, the result landed as a direct blow to Chancellor Friedrich Merz, who watched the count from CDU headquarters without addressing the public.

General secretary Franziska Hoppermann called it "a very difficult result for us," while state premier Sven Schulze offered only muted congratulations to AfD.