South Korea's presidential office said Tuesday that a "significant portion" of information contained in reportedly leaked classified Pentagon documents that detail apparent U.S. spying on Seoul are fake, a stance that the allies’ defense chiefs also agreed on in a phone call.

Seoul's announcement comes after top secret U.S. Defense Department documents leaked online reportedly revealed American intelligence-gathering efforts on allies, including South Korea.

In a phone call Tuesday, the South Korean and U.S. defense chiefs agreed that "a significant number of the documents in question were fabricated," the presidential office in Seoul said in a statement.

The statement did not offer specifics on what information in the documents was false, but said Washington and Seoul would work to strengthen trust and cooperation on the matter going forward.

The Pentagon has said it is working to determine the veracity and provenance of the documents, with at least some of them believed to have been altered.

Queried on the matter, the Pentagon said the phone call between U.S. Defense Secretary Lloyd Austin and South Korean Defense Minister Lee Jong-sup did take place, but it did not offer further comment as of this story’s publication.

Many of the leaked documents, which were posted recently to social media, largely focused on the war in Ukraine, with one in particular reportedly offering details about concerns inside the administration of South Korean President Yoon Suk-yeol over an apparent move by Washington to strong-arm Seoul into supplying Kyiv with ammunition — despite a law that bans the sales of arms to countries embroiled in conflict.

While South Korea had reportedly agreed to sell artillery shells to help the U.S. replenish its own dwindling stockpiles, it insisted that their “end user” should be the American military. Top aides to Yoon, however, were worried that Washington would ultimately divert them to Kyiv, according to one of the secret documents, The New York Times reported.

The document was based on signals intelligence, according to the Times, meaning that the United States had been spying on one of its top allies in Asia.

The reports of U.S. wiretapping of a key ally have sparked concerns over the health of the alliance, especially as they come just three weeks before Yoon's April 26 state visit to Washington for summit talks with President Joe Biden.

South Korean officials, however, have thrown cold water on the reports of U.S. spying, with the presidential office labeling them "absurd and false" and calling the security system at the office "watertight."

Asked about the impact of the alleged wiretapping on U.S. allies and partners, a State Department spokesman said Monday in Washington that officials were working to prevent any negative repercussions, but did not confirm the allegations.

“U.S. officials are engaging ... with our allies and partners over this to reassure them as it relates to our commitment to safeguard intelligence and sensitive documents as well as ensuring our commitment to the security of the partnerships that we have with these countries,” spokesman Vedant Patel said.

This is not the first time South Korea has grappled with U.S. spying allegations.

In 2013, Seoul asked Washington to probe reports based on leaked documents by former U.S. National Security Agency contractor Edward Snowden that said Seoul’s Embassy in the United States had been targeted by the NSA, which tapped their phone calls and emails.