AfD party flag in Germany
© Fabrizio Bensch / Reuters
The deputy chief of the German anti-immigrant and Euroskeptic Alternative for Germany (AfD) party has vowed it will become the third largest force in the 2017 federal parliamentary elections, following its latest breakthrough in the Berlin polls.

Celebrating the outcome, AfD deputy leader Beatrix von Storch published a post saying the result is a sign of "decline" for Chancellor Angela Merkel's Christian Democratic Union (CDU) party.

"The CDU declines. The AfD rises. In 2017 we'll see Angela Merkel fighting for her political survival and the AfD will become the third-largest force in Germany - at least," Storch wrote.

The far-right AfD took 14.1 percent of the vote in Berlin parliamentary polls, according to the latest preliminary results. It's the first time the AfD has participated in Berlin elections since the party's establishment in 2013. However the party is already present in nine out of 16 state parliaments in Germany.

Merkel's CDU came second, beating the AfD but losing 5 percent of voters compared to the previous elections in the German capital, according to Focus German magazine.

Following the release of the polls, Merkel said she "takes responsibility for the outcome." She also admitted her government was "not prepared" for the refugee crisis - a point considered key to the AfD success across Germany.

"If I could, I would turn back time many, many years to better prepare myself, the whole federal government and all those in positions of responsibility for the situation we were rather unprepared for in the late summer of 2015," Merkel stated.

She went on to say that the refugee influx in 2015 was "out of control" at certain moments. "[I] repeated the 'We can make it' [phrase] far too often," Merkel said, commenting on her oft-quoted statement with regard to the refugee and migrant crisis.

Critics have directly connected the AfD's gains with Merkel's open-door policy towards refugees.

"The result for the CDU in Berlin is not only self-inflicted, Merkel has indeed a [great] share [in it]. Without her no AFD," a tweet read.

Following the election, the CDU still reiterated that it had at least managed to place ahead of the AfD.

"Not having placed behind the AfD as in Shwerin [State of Mecklenburg-Western Pomerania] is considered by the CDU a success - no words left," a Twitter user commented.

Earlier in September, the AfD beat the CDU and snatched second place during the local elections in Merkel's homestate of Mecklenburg-Western Pomerania.

"Merkel crushed in elections in Berlin - Germans have had enough of her mad open borders," was one of the comments Merkel's critics posted on social media.

Some argued though that Merkel's policies are not related to the rise of the AfD.

Others issued rather worrying comments, hinting at the alleged similarities between the far-right AfD and Nazi-era Germany.

"I am asking myself, whether there is a rising stupidity among the nation? People forget too quickly. Hitler has not been dead for even 100 years."

The ruling Berlin mayor, Michael Muller, said on Sunday that the success of the AfD would indicate "the return of Nazism" in Germany.