Copenhagen. Denmark on Thursday summoned the top American diplomat in the country for an explanation following a Wall Street Journal report about the United States stepping up intelligence gathering on Greenland, a semi-autonomous Danish territory coveted by US President Donald Trump.

Jennifer Hall Godfrey, acting head of the US Embassy in Copenhagen, met with high-ranking Danish diplomat Jeppe Tranholm-Mikkelsen at the Danish Foreign Ministry over the Journal article published Tuesday, the ministry said in an email.

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

The Journal, citing two people familiar with the US effort that it did not identify, reported that several high-ranking officials under the US director of national intelligence, Tulsi Gabbard, had directed intelligence agency heads to learn more about Greenland’s independence movement and sentiment about US resource extraction there.

Danish Foreign Minister Lars Lokke Rasmussen told broadcaster DR outside a meeting Wednesday with colleagues in Poland that Denmark would summon the US diplomat to seek a “rebuttal” or other explanation following the report.

Rasmussen, who has previously scolded the Trump administration over its criticism of NATO ally Denmark and Greenland, said the information in the report was “very worrying" and "we don’t spy between friends.”

"We are looking at this with quite a lot of seriousness," he added.

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. Nearly a dozen more leak cases are being investigated, Gabbard said in the statement.

“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 US 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.”

In a visit to the island last month, Denmark’s Prime Minister Mette Frederiksen said, addressing the United States during a visit to Greenland, that “you cannot annex another country,” even with the argument made by US officials that international security is at stake.

US Secretary of State Marco Rubio has said Washington will respect Greenland’s self-determination and alleged that Greenlanders "don’t want to be a part of Denmark.”