BERLIN (Reuters) - The editor-in-chief of Der Spiegel on Sunday said a front cover illustration of U.S. President Donald Trump beheading the Statue of Liberty, which split opinion at home and abroad, was a response by the German magazine to threats against democracy.

Published on Saturday, the cover depicts a cartoon figure of Trump with a bloodied knife in one hand and the statue's head, dripping with blood, in the other. It carries the caption: "America First".

It followed a series of attacks on Berlin's policies by Trump and his aides that have marked a rapid deterioration in German relations with the United States.

"Der Spiegel does not want to provoke anybody," editor-in-chief Klaus Brinkbaeumer told Reuters TV after the cover set off a debate on Twitter and in German and international media, adding he was surprised by the impact of the illustration.

"We want to show what this is about, it's about democracy, it's about freedom, it's about freedom of the press, freedom of justice and all that is seriously endangered," he said.

"So we are defending democracy... Are these serious times? Yes they are."

Alexander Graf Lambsdorff, a member of Germany's Free Democrats (FDP) and vice president of the European Parliament, described the cover as "tasteless".

Die Welt said it "damages journalism", while another German daily, the Frankfurter Allgemeine Zeitung, said it was "exactly what Trump needs - a distorted image of him, which he can use to work more on his distorted image of the press."

Karl-Georg Wellmann, a lawmaker for Chancellor Angela Merkel's CDU conservatives, told mass-selling daily Bild: "I urge everyone to calm down and to handle this with reason, rather than gut feeling."

Merkel was the go-to European ally for former U.S. president Barack Obama, who praised her as "an outstanding partner".

But Trump has said she made a "catastrophic mistake" with her open-door migration policy, and his top trade adviser last week accused Germany of using a "grossly undervalued" euro to gain advantage over the United States and its European partners.

(Reporting by Reuters TV; Writing by Paul Carrel; editing by John Stonestreet)