Danish Prime Minister Mette Frederiksen told The Associated Press "you cannot spy against an ally" after reports that the United States has stepped up intelligence gathering on Greenland, a semi-autonomous Danish territory coveted by President Donald Trump.

Denmark on Thursday summoned the top American diplomat in the country for an explanation following a Wall Street Journal report which said several high-ranking officials under the U.S. director of national intelligence, Tulsi Gabbard, had directed intelligence agency heads to learn more about Greenland's independence movement and sentiment about U.S. resource extraction there.

Jennifer Hall Godfrey, acting head of the U.S. Embassy in Copenhagen, met with high-ranking Danish diplomat Jeppe Tranholm-Mikkelsen at the Danish Foreign Ministry, the ministry said in an email.

It provided no further details. The embassy declined to comment.

Frederiksen said Friday the report was "rumors" in an international newspaper. The Journal cited two people familiar with the U.S. effort which it did not identify.

In response to questions about the Journal's report, Gabbard's office released a statement noting that she had made three "criminal" referrals to the Justice Department over intelligence community leaks.

"The Wall Street Journal should be ashamed of aiding deep state actors who seek to undermine the President by politicizing and leaking classified information," Gabbard wrote. "They are breaking the law and undermining our nation's security and democracy. Those who leak classified information will be found and held accountable to the fullest extent of the law."

Greenland's prime minister said last month that U.S. statements about the mineral-rich Arctic island have been disrespectful and it "will never, ever be a piece of property that can be bought by just anyone."