President Donald Trump is interested in buying Greenland, the world's largest island, and has asked his White House legal adviser to consider the idea, The Wall Street Journal reported Friday.

The paper quoted two unnamed advisers as saying that Trump had asked them, along with other advisers, in passing debates whether any such move was possible, adding that the US president was following with interest the talk about Greenland's resources and geopolitical importance.

A number of advisers expressed support for the move as "economically viable," according to the Wall Street Journal to exporters, while others considered it just an idea that admires Trump.

It is unclear how the United States can buy Denmark's autonomous Greenland?

The State Department on Greenland responded to Trump's desire to buy the island because it and its residents are not for sale. "The island is rich in natural resources such as minerals, clean water, renewable energy and tourism. We are open to trade cooperation but we are not for sale," it said in a statement.

Around 56,000 people live on the ice-covered island between the North Atlantic and the Arctic Ocean and follow its foreign and security policy for Copenhagen.

There was no comment from the White House on the Wall Street Journal.