President Donald Trump has spoken with German Chancellor Angela Merkel - the European leader whom he criticised for her policy of welcoming refugees from Syria.

In 2015, Mr Trump tweeted that the German chancellor was “ruining Germany.”

Similarly, he compared his opponent Hillary Clinton to Angela Merkel, saying she wants to “be America’s Angela Merkel and you know what a disaster the massive immigration has been to Germany and the people of Germany.”

German Chancellor Angela Merkel attends a session of the German Bundestag (lower house of parliament) in Berlin (Getty Images)

However, in 2016, Mr Trump picked Ms Merkel as his favourite world leader, despite his criticism of her position on refugees.

“Well, I think Merkel is a really great world leader, but I was very disappointed [in] this move with the whole immigration thing,” he said in New Hampshire in September, according to New England Cable News.

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More recently, in an interview with Germany’s Bild and the Times, Mr Trump again said he respected Ms Merkel but that she made a “catastrophic mistake” and referred to a Tunisian asylum seeker who drove through a Christmas market killing 12 people.

Ms Merkel and Mr Trump spoke bout NATO, the situation in the Middle East and North Africa, their ties to Russia and the conflict in eastern Ukraine, according to a statement approved by both countries.

“The leaders recognised that NATO must be capable of confronting 21st century threats and that our common defence requires appropriate investment in military capabilities to ensure all allies are contributing their fair share to our collective security,” it said.

Former President Barack Obama also admired Ms Merkel and his last phone call as president was to Ms Merkel and during a press conference before leaving office, Mr Obama praised her work as she considers running for re-election in September.

“That’s a matter for the German people, but I value Angela’s leadership,” said Mr Obama on whether she should be re-elected.