Julian Assange participates in a live question-and-answer session via Skype at a meeting in Melbourne / AFP\Getty

Update: The files have now been released – read about it here

WikiLeaks is about to release a huge, mysterious trove of documents, according to Julian Assange.

Update: Wikileaks has now released the documents

The organisation's official Twitter, which is thought to be run by its leader, posted a link to a trove of documents early in the morning. It promised that the password to unlock them would be revealed later on, at 9am eastern time.

The post didn't make any explicit reference to what was contained in the document, making reference only to mysterious phrases like "Year Zero" and "Vault 7". But the post included a hidden picture that appeared to make reference to a secret CIA code.

When the announcement's colours were altered, it revealed a picture of the Lingua sculpture that is at a convention centre in Washington. The clear parts of the image show Chinese text, but the large sculpture itself includes words from a wide range of languages and historical documents.

That same sculpture was made by Jim Sanborn, the person behind the Kryptos sculpture that is housed at the CIA headquarters in Virginia. Nobody knows what the writing on that sculpture actually says, since the message is encrypted in a secret code to which only the sculptor and the head of the agency are thought to have access.

Trump once said he 'loved' Wikileaks

Some teasers from WikiLeaks have suggested that it could be about to release information about the CIA. Online speculation has suggested a wide array of possibilities but it is possible that the documents could reveal nothing at all.

WikiLeaks last large leak was of the Podesta files, or the emails stolen from Hillary Clinton campaign manager John Podesta. Those files, thought to have been accessed through a hack of the Democratic party by people based in Russia, were in part credited with Donald Trump's election.

More recently, Mr Assange has called for the leak of important political documents including Mr Trump's unpublished tax returns and files on the French election.

Julian Assange continues to live inside the Ecuadorian embassy, where he has been for years avoiding questioning in Sweden over a rape charge that he claims will be used to extradite him to the US. He had initially promised to leave the embassy if Chelsea Manning's sentence was commuted – but has since seemed to back down from that promise.