The United Nations has officially expressed concern to the U.S. over reported surveillance on UN Secretary-General Antonio Guterres, a UN spokesperson said on Tuesday after The Washington Post, citing leaked classified intelligence documents, reported that the U.S. eavesdropped on conversations of Guterres and other UN officials.

"UN officially expressed to the host country its concern regarding recent reports that the communications of the secretary-general and other senior UN officials have been the subject of surveillance and interference by the U.S. government," said Stephane Dujarric, spokesperson for Guterres.

"The UN has made it clear that such actions are inconsistent with the obligations of the United States of America enumerated in the UN Charter and the Convention on the Privileges and Immunities of the United Nations," he added.

The four leaked documents, two of which haven't been previously reported, summarize intercepted conversations that shed new light on the UN chief's interactions with top UN officials and world leaders, the newspaper reported.

In one document dated February 17 and seen by the newspaper, Guterres expressed to UN officials and world leaders his "outrage" over being denied an opportunity to visit Ethiopia's war-torn Tigray Region.

The secretary-general wanted to confront Ethiopian UN Representative Taye Atske Selassie Amde as the country's foreign minister, Demeke Mekonnen, sent Guterres a letter rejecting his planned visit to Tigray amid peace negotiations, the newspaper said.

Another document obtained by the newspaper revealed that Guterres was "not happy" about having to travel to Kyiv to meet Ukrainian President Volodymyr Zelenskyy in early March. While the document didn't provide a reason for the secretary-general's unwillingness, The Post cited a UN diplomat as saying weeks of tiring international travels on commercial flights was the cause.

The trove of leaked classified documents, numbering hundreds of pages and resulting in the arrest of a U.S. air national guardsman on charges of disclosing classified national defense information without authorization, has seen the U.S. scramble to assess the damage and restrict access to classified information for certain employees at the Department of Defense.

Other documents recently reported by U.S. media showed the U.S. has also been spying on allies such as South Korea, Israel and Ukraine.

Asked by Xinhua at a Brookings Institution event on Monday to comment on allegations of U.S. spying efforts and on how Washington should soothe the concerns expressed by its allies, Democratic House Representative Abigail Spanberger refused to comment on "anything specifically that was leaked."

The congresswoman, who prior to becoming a lawmaker worked as an operations officer at the Central Intelligence Agency, praised the U.S. administration's "commitment to safeguarding the information that we collect and our commitment to safeguarding the information (U.S. allies) collect and provide to us."

(With input from Xinhua)