Greenland has once again said it is not for sale after US President-elect Donald Trump said he wanted to take control of the territory.

"Greenland belongs to the people of Greenland," its prime minister said on Monday, a day after Trump repeated comments about the Arctic island that he first made several years ago.

Greenland, which is an autonomous Danish territory, is home to a large US space facility and lies on the shortest route from North America to Europe, meaning it is strategically important for the US.

There was no immediate response to Trump's comments from Denmark.

Writing on his social media platform, Truth Social, on Sunday, the US president-elect said: "For purposes of National Security and Freedom throughout the World, the United States of America feels that the ownership and control of Greenland is an absolute necessity."

His comments prompted a sharp rebuke from Greenland's Prime Minister Mute Egede, who said: "We are not for sale and we will not be for sale."

"We must not lose our long struggle for freedom. However, we must continue to be open to co-operation and trade with the whole world, especially with our neighbours," he said.

Trump's controversial remarks came hours after he announced that he intended to nominate Ken Howery, his former ambassador to Sweden, to be the new ambassador to Denmark.

Mr Howery said he was "deeply humbled" by the nomination and looked forward to working with the staff at the US embassy in Copenhagen and the US consulate in Greenland to "deepen the bonds between our countries".

Trump's original suggestion in 2019 that the US acquire Greenland, which is the world's largest island, led to a similarly sharp rebuke from leaders there.

The then Danish Prime Minister Mette Fredericksen, who still holds the role, described the idea as "absurd", leading Trump to cancel a state trip to the country.

He is not the first US president to suggest buying Greenland. The idea was first mooted during the 1860s under the presidency of Andrew Johnson.

Separately on Sunday, Donald Trump threatened to reassert control over the Panama Canal, one of the world's most important waterways - accusing Panama of charging excessive fees for access to it.

Panama's president later said "every square metre" of the canal and surrounding area belonged to his country.