Danish politicians dismissed the notion of selling Greenland to the United States following reports that US President Donald Trump had privately discussed the idea of buying the world's biggest island. Mr Trump is due to visit Copenhagen in September and the Arctic will be on the agenda during meetings with the prime ministers of Denmark and Greenland, which is an autonomous Danish territory. "It has to be an April Fool's joke. Totally out of season," former prime minister Lars Lokke Rasmussen said on Twitter. The notion of purchasing the territory has been laughed off by some advisers as a joke but was taken more seriously by others in the White House, two sources told Reuters. Talk of a Greenland purchase was first reported by the <em>Wall Street Journal</em>. "If he is truly contemplating this, then this is final proof that he has gone mad," foreign affairs spokesman for the Danish People's Party, Soren Espersen, told broadcaster DR. "The thought of Denmark selling 50,000 citizens to the United States is completely ridiculous," he said. Greenland, a self-ruling part of Denmark located between the North Atlantic and Arctic oceans, is dependent on Danish economic support. "I am sure a majority in Greenland believes it is better to have a relation to Denmark than the United States, in the long term," said Aaja Chemnitz Larsen, the Danish MP from Greenland's second-largest party Inuit Ataqatigiit (IA). "My immediate thought is 'No, thank you'," she said. Prime Minister Mette Frederiksen and Foreign Minister Jeppe Kofod were not available for comment but officials said they would respond later on Friday. "Oh dear lord. As someone who loves Greenland, has been there nine times to every corner and loves the people, this is a complete and total catastrophe," former US ambassador to Denmark, Rufus Gifford, said on Twitter. Greenland is gaining attention from global super powers due to its strategic location and its mineral resources. A defence treaty between Denmark and the United States dating back to 1951 gives the US military rights over the Thule Air Base north of the island. Greenland is part of Denmark with self-government over domestic affairs, while Copenhagen handles defence and foreign policy. There has been no indication that a Greenland purchase will be on the agenda for Mr Trump's talks with Danish officials. Martin Lidegaard, senior politician of the Danish Social Liberal Party and a former foreign minister, called the idea "a grotesque proposal" which had no basis in reality. "We are talking about real people and you can't just sell Greenland like an old colonial power," he said. "But what we can take seriously is that the US stakes and interest in the Arctic is significantly on the rise and they want a much bigger influence." It's not like the US has toyed with buying Greenland before. In 1946, then president Harry Truman floated the idea of swapping Alaska for the island and had offered Denmark $100m for the territory. In 1917 Denmark sold off the then Danish West Indies islands for $25m to America, which renamed them the US Virgin Islands.