Furiously denying the explosive claims in the file as “phony stuff”, America's incoming 45th president on Wednesday said the leak was “something that Nazi Germany would have done and did do”.

“To be honest, about your question about the comparison with Nazi Germany, I am as perplexed as you are, I can't interpret that,” Steinmeier responded in a press conference to a question on Trump's comment.

The focus of the president elect's hour-long press conference on Wednesday was the unsubstantiated claims that his aides colluded with the Kremlin to win the US election, and that Russia has compromising information on Trump.

Steinmeier, 60, has emerged in recent months as the German government's most strident detractor of Trump.

He warned a day after Trump's shock election that relations would become “more difficult” with the United States making more decisions “on its own”.

During the US campaign, Steinmeier was even more damning, saying the prospect of a Trump presidency was a “frightening” for the world.

He compared Trump to a “hate preacher”, saying he had much in common with “fearmongers” in Germany's right-wing populist AfD party and advocates of Britain's exit from the EU.

Steinmeier said that based on Trump's first press conference since his election, it was not possible to draw conclusions on the foreign policy directions that his administration would take.

But he predicted that at some point, Trump would ease off on his penchant for communicating through Twitter.

“Each president must find his own style and President Trump will do that too. I can't imagine that these Twitter messages will go on for long, in any case I'm not in a position to formulate a foreign policy concept in 140 characters,” said Steinmeier.

Trump has turned to Twitter to express views as widely ranging as accusing China of military expansionism to hitting out at veteran actress Meryl Streep over her criticisms to demanding that Mexico pay for a border wall.