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Prof Hans-Werner Sinn, 68, is one of Germany’s leading economic experts and serves on the Advisory Council of the Ministry of Economics, cited research saying that the migrant crisis in Germany had cost the country in the region of £17billion (20bn euros) and would cost the country around £340bn (400bn euros) in the long-term. Before retiring he held the chair of Economics and Public Finance at the University of Munich.

EPA/Getty German Chancellor Angela Merkel has come under fire over her migrant policy

Prof Sinn, speaking to The European magazine, said: “The Chancellor’s action can be justified for humanitarian reasons, but it was a flagrant violation of the right to asylum which prevents refugees from coming to Germany via safe third countries in order to apply for asylum there. “Refugees who are seized at the border are to be rejected, it is said unequivocally in law. “The Chancellor should have asked the Bundestag [parliament] to change the Asylum Act and the Basic Law, but she did not.”

Reuters Angela Merkel attended the Munich Security Conference recently

Getty Around one million migrants are estimated to have arrived in Germany

Refugees who are seized at the border are to be rejected, it is said unequivocally in law Prof Hans-Werner Sinn

He added Germany did not cope well with the huge numbers of migrants which made their way to the country, with around one million people estimated to have come to the country in 2015 alone. The professor said: “We could not stand it [a second migrant wave]. We can not even stand the first one well.” Prof Sinn, the author of the books Casino Capitalism and The Green Paradox, cited research by Prof Bernd Raffelhüschen, who is the professor of Economics at the University of Freiburg, who estimated the current cost of the migrant crisis was £17bn.

Migrant crisis: Key locations before and after Tue, April 4, 2017 In these composite images, a comparison has been made between a scene at a key location during the height of the 2015 migrant crisis last year and the view there now Play slideshow Getty Images 1 of 10 Aid workers help migrants up the shore after making the crossing from Turkey to the Greek island of Lesbos on November 16, 2015 in Sikaminias, Greece

At the time, Prof Raffelhüschen said: "Politicians now have to ensure the best possible integration to at least curb the costs partly. "Germany can't afford uncontrolled immigration permanently."

Getty Angela Merkel visited a migrant shelter and school in 2015

Getty Migrants given shelter and food having arrived in Germany