Anti-EU party continues to poach Merkel votes

Both of the mainstream parties lost more than 5 percent compared to their previous result.

The outcome meant that the two factions, which are allied at the federal level, no longer have a majority in the city, prompting speculation that the SPD would join up with the far-left Die Linke (15%) and the Greens (15%) instead.

The anti-immigrant and anti-EU AfD party came fifth, but its score, of almost 14 percent, saw it enter the regional assembly for the first time.

It did better still in east Berlin, which is financially less well off than the west, and where it came third on 17 percent after Die Linke (24%) and SPD (19%), beating Merkel's CDU (13%).

The results prompted hand-wringing in Merkel’s bloc.

Frank Henkel, the CDU's top candidate for Berlin, said it was "a black day” and that "it is very alarming when fringe parties like the AfD or Die Linke between them attract a quarter of the vote."

Monika Gruetters, another leading CDU candidate, called it “a sad day for the popular parties”.

Markus Soeder, a leading figure in the CDU’s sister party, the CSU in Bavaria, blamed the outcome on Merkel’s policy of welcoming refugees, saying she must “regain citizens' support on the refugee question and finally strictly limit immigration and get a handle on the security problems”.

But the AfD’s Berlin front-man, Georg Pazderski, celebrated the fact that his side had come “from zero to double-digits”.

The party’s co-leader, Beatrix von Storch, called it “a huge success”. “We've arrived in the capital," she said.

Analysis showed that the AfD picked up the most votes from people who had not voted before (53,000) or from former CDU supporters (32,000).

The Berlin outcome meant it now has a presence in 10 out of Germany’s 16 regional assemblies ahead of next year's federal election.

It also made headlines two weeks ago by beating the CDU into third place in Merkel's home region of Mecklenburg-Vorpommen, a poor part of eastern Germany.