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Following the deadly Berlin terror attack on Monday evening, the Chancellor's leadership has been called into question. Berlin police are still chasing a suspected armed perpetrator, after a lorry was driven into a crowded Christmas market, killing 12 and injuring dozens more. Mrs Merkel was widely criticised after she allowed one million migrants, many of whom were unvetted, into Germany in 2015. Stefan Kornelius, who wrote 'The Chancellor and Her World' in 2013, told BBC Radio 4’s Today programme that Mrs Merkel won’t solely blame her immigration policy for the terrorist attack.

GETTY Angela Merkel's position has been called into question following the Berlin terror attack

I don’t think she will feel that personally she is responsible for the Berlin terror attack Stefan Kornelius

Her biographer said: “There is a lot of talk, especially from the right-wing populist party here and her fierce opponents within her own party that she bares this responsibility. “I don’t think she will feel that personally – she would definitely say terrorism can come from all sides of this new environment. We can see it from migrants – there’s a lot of homegrown terrorism.” Mr Kornelius continued: “I don’t think you can draw a direct line from the huge number of people coming in within half a year in 2015. “However Angela Merkel a couple of times said she regrets not having acted much earlier on the refugee crisis because definitely, it changes a society very much if you allow one million people into the country in one year.”

GETTY The German Chancellor will not feel responsible for the attack, according to her biographer

He continued to say that the German Chancellor will want to “present herself as a safe pair of hands” as she seeks a fourth term in office after the German elections next year. “This kind of calm and stability is something that could be extremely appealing to the German electorate,” insisted Mr Kornelius. He also predicted events could see her shift more of her policies to the right in order to win over the country again. Mrs Merkel may have to introduce a cap of migrants arriving in the country if immigration and the migrant crisis becomes a "decisive" issue in the 2017 elections.

GETTY Twelve people were killed and scores more injured as a lorry smashed into a Christmas market

Speaking the day after the attack Mrs Merkel said: “It would be a very difficult for us to learn that a human being committed this deed who came to Germany to ask for refugee and asylum.” German ministers have turned on her with even members of her own party pinning blame on her for the attack. In an attack on the Chancellor’s open-door refugee policy, Klaus Bouillon of Mrs Merkel’s CDU party told Saarland radio: “We must state that we are in a state of war, although some people who want to see only the good can not see.” Mr Bouillon announced intensified security measures amid fears of further attacks, he added: “We will take it wherever we think it is necessary.

“That means long-range weapons, short weapons, machine guns, even if this sounds martial.” The chief executive of the populist right-wing Alternative for Germany party, which is hopeful of gaining seats in next year's elections, has claimed the country is no longer safe. AfD chairwoman, Franke Petry, blamed the federal government for the alleged attack insisting they could have done more.

BERLIN TERROR: 'TWELVE' dead as truck crashed into crowd at Christmas market Tue, December 20, 2016 A truck crashed into a Christmas market in Berlin killing at least 12 and injuring 48 Play slideshow REUTERS•AFP 1 of 21 A truck crashed into a Christmas market in Berlin killing at least 12 and injuring 48