BERLIN, Sept. 19 (Xinhua) — German Chancellor Angela Merkel's CDU party was hit by a second electoral blow in two weeks in the Berlin state-city vote on Sunday, highlighting an increasing pressure on her open-door refugee policy.

The loss Merkel's conservative party suffered in the Berlin polls, following the vote in early September in the eastern state of Mecklenburg-Vorpommern, turned largely into a gain for the anti-immigrant Alternative of Germany (AfD).

In Sunday's vote, support for the Christian Democratic Union dropped to 17.6 percent from 23.3 percent in the last election in 2011, the lowest since 1990. Meanwhile, a 14.2 percent of the vote enabled the three-year-old right-wing AfD to enter Berlin's state parliament, the 10th among Germany's 16 states.

Berlin's traditionally strongest Social Democrats also recorded a fall in support, to a record low of 21.6 percent from 28.3 percent, and is unlikely to continue the current coalition with their junior partner, the CDU.

With one year away from a federal election, the outcome raised pressure on Merkel as well as doubt about a fourth term for the most powerful leader in the European Union.

It adds fuel to the dispute over Merkel's migrant policy between Christian Democrats and their traditional ruling partner, the Christian Social Union (CSU) in Bavaria, whose call for an annual cap of 200,000 refugees has been rejected by Merkel.

The CSU's Bavarian finance minister Markus Soeder called the Berlin vote result another "massive wake-up call".

"A long-term and massive loss in trust among traditional voters threatens the conservative bloc," he told the Bild daily, while urging changes in Merkel's migrant policy to win back support.

Berlin hosts over 70,000 of the 1 million asylum seekers Germany took in last year. German media reported that a poll found about 22 percent of those voting for the AfD in Berlin supported the CDU in 2011.

"From zero to double digits, that's unique for Berlin. The grand coalition has been voted out — not yet at the national level, but that will happen next year," said AfD candidate Georg Pazderski to supporters after the Sunday results.

Berlin's SPD Mayor Michael Mueller had warned before the vote that a strong AfD result would be "seen throughout the world as a sign of the resurgence of the right and of Nazis in Germany."