South Korea said on Tuesday that specific information contained in a leaked US confidential document that appeared to be based on internal discussions among top South Korean security officials is "untrue" and "altered".

A security breach exposed secret US documents, at least one of which was labeled "top secret", detailing US and NATO plans for Ukraine's spring offensive against Russia, sparking a diplomatic debacle between the US and its allies.

One of the documents detailed internal discussions between South Korean officials about American pressure on Seoul to assist in providing weapons to Ukraine, raising the possibility that the United States may have been spying on South Korea, one of its key allies, and drawing criticism from the Asian country's lawmakers.

Seoul and Washington concurred that much of the leaked information against South Korea has been fabricated, Deputy National Security Adviser, Kim Tae-hyo, told reporters following phone conversations between US Secretary of Defense Lloyd Austin and his South Korean counterpart on Tuesday.

However, Kim did not specify what specific information in the document was false.

The Pentagon chief talked about recent media reports on the leak and promised to carefully cooperate with South Korea on the matter during the phone conversation that took place at Austin's request, as per the South Korean Defense Ministry.

The US spy leak scandal comes just weeks before Yoon is expected to meet with US President Joe Biden in Washington on April 26.

Some lawmakers of South Korea's main opposition Democratic Party voiced "strong regret" on Monday over the leak, referring to it as a clear violation of national sovereignty and a major security failure of the Yoon administration.

The leaks revealed that South Korea had agreed to send artillery shells to the United States in order to help it restock its ammo. South Korea insisted that the "end user" should be the American military. However, senior South Korean officials were concerned internally that the US would send them to Ukraine.

According to South Korea, sending weapons to a country at war violates its own laws, hence it cannot deliver weapons to Ukraine.

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