The United States is scrambling to identify the source of a possible leak of highly-classified documents that appear to reveal sensitive details about US allies, including Ukraine’s vulnerabilities in its war with Russia.

The Pentagon said on Sunday it had made a formal referral to the Department of Justice, asking it to investigate the apparent leak of the documents, which have been circulated on social media sites, including Twitter.

The documents, which resemble non-public daily updates produced by the US military’s Joint Staff, appear to contain intelligence related to Ukraine, China, the Middle East and Africa.

The leak appears to show Washington spying on close US allies, including Ukraine, South Korea and Israel, a potentially embarrassing revelation for the administration of US President Joe Biden.

However, the documents appear to contain at least some errors, including battlefield casualty estimates that minimise Russian losses.

US officials have told the Reuters news agency they have not ruled out the possibility the documents have been doctored to conceal their origin or spread false information that could damage US security interests.

The Ukrainian presidential office has said the leaked documents contain a large amount of “fictitious information” and bear the hallmarks of a Russian disinformation campaign.

One document marked “Secret” and dated February 23 describes how Ukraine’s air defence systems are on track to run out of munitions by May if they continue going through stockpiles at the current rate.

Another document claims that Israel’s Mossad intelligence agency encouraged protests against Israeli Prime Minister Benjamin Netanyahu’s controversial judicial reforms, which Netanyahu’s office on Sunday said was “without any foundation whatsoever”.

In another document, senior South Korean officials are said to have discussed coming under US pressure to help supply weapons to Ukraine in violation of Seoul’s policy against exporting weapons to countries in conflict.

A South Korean presidential official on Sunday acknowledged the reports about the leaked documents and said it would raise the issue with Washington. (Al Jazeera)

•The United States Department of Justice is investigating the source of a possible leak of highly-classified documents [File: Al Drago/Reuters]

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