Frauke Petry, head of the eurosceptic Alternativ fuer Deutschland (AfD) party, told a regional newspaper: "I don`t want this either. But the use of armed force is there as a last resort."
Her comments were condemned by leftwing parties and by the German police union.
More than 1.1 million migrants arrived in Germany last year.
Also on Saturday, German Chancellor Angela Merkel said most migrants from Syria and Iraq would go home once the wars in their countries had ended.
She told a conference of her centre-right CDU party that tougher measures adopted last week should reduce the influx of migrants, but a European solution was still needed.
German police `should shoot migrants`, populist politician says
31 January 2016
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German police should "if necessary" shoot at migrants seeking to enter the country illegally, the leader of a right-wing populist party has said.
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