Instant messaging platform Discord said on Wednesday it was cooperating with US law enforcement’s investigation into a leak of secret US documents that has grabbed attention around the world.

The statement comes as questions continue to swirl over who leaked the documents, whether they are genuine, and whether the intelligence assessments in them are reliable.

The documents, which carry markings suggesting that they are highly classified, have led to a string of stories about the war in Ukraine, protests in Israel, and how the US surveils friend and foe alike.

The source of the documents is not publicly known but reporting by the open-source investigative site Bellingcat has traced their earliest appearance to Discord, a communications platform popular with gamers.

Discord's statement suggested it was already in touch with investigators.

"In regards to the apparent breach of classified material, we are cooperating with law enforcement," the statement said.

"As this remains an active investigation, we cannot provide further comment at this time."

The Federal Bureau of Investigation did not immediately return a message seeking comment.

Although the documents only began drawing attention recently, Bellingcat said it found evidence that at least some of the files had been floating around on social media as far back as March or even January.

Bellingcat cited Discord users who it said gave similar accounts of the documents' provenance but cautioned that it was unable to independently verify all the information they shared.

Reuters could not immediately corroborate Bellingcat's reporting; attempts to reach former members of the server via the social media site Reddit and other servers on Discord were not immediately successful.

- Reuters