King Frederik of Denmark has expressed congratulations to new United States President Donald Trump amid an escalating diplomatic dispute over Greenland.

Mr Trump was inaugurated as the United States’ 47th President on Monday local time after defeating Democrat incumbent Joe Biden in November’s election.

The Danish monarch, who is married to Australian-born Queen Mary, personally congratulated the new president in a letter shared via the Danish royal household’s social media accounts on Tuesday.

“The Honorable Donald J. Trump, President of the United States of America,” the Danish monarch wrote.

“On the occasion of your inauguration on January 20th, 2025, as the 47th President of the United States of America, I wish to express my sincere congratulations and best wishes for yourself, your family and for the people of the United States of America.”

The Danish monarch was one of a number of royals who formally congratulated the new President, including King Carl Gustaf of Sweden.

Frederik’s letter comes amid diplomatic tensions between Denmark and the Trump administration over the new president’s desire to take control of Greenland.

The world’s largest island is a partially self-governed arctic territory under the Danish Crown but Mr Trump has earmarked the island as vital for “national security purposes”.

Denmark’s Prime Minister Mette Frederiksen has told Mr Trump that it is up to Greenland to decide its own future, while Mr Trump is threatening to introduce tariffs on Denmark over the spat.

Denmark is often cited as an example of progressive left-wing style government thanks to its high income taxes, low income inequality and universal healthcare.

However, Copenhagen has also pursued some of the harshest anti-immigration policies in the European Union, including revoking hundreds of visas from mostly Syrian refugees since 2019.

The ruling Social Democratic Party has also floated banning hijabs in Danish schools after the country earlier banned the burqa in 2018.