WikiLeaks founder Julian Assange has been charged in the United States, the organisation said, in a development that could have implications for Robert Mueller’s probe into alleged Russian meddling in the US presidential election.

Prosecutors inadvertently disclosed the existence of a sealed indictment in a court filing in an unrelated case, WikiLeaks said.

The exact nature of the charges against Assange was not immediately known.

SCOOP: US Department of Justice "accidentally" reveals existence of sealed charges (or a draft for them) against WikiLeaks' publisher Julian Assange in apparent cut-and-paste error in an unrelated case also at the Eastern District of Virginia. https://t.co/wrjlAbXk5Z pic.twitter.com/4UlB0c1SAX — WikiLeaks (@wikileaks) November 16, 2018

The still-unsealed charges against Assange were revealed by Assistant US Attorney Kellen Dwyer as he made a filing in the unrelated case and urged a judge to keep that filing sealed.

Dwyer wrote: “Due to the sophistication of the defendant and the publicity surrounding the case, no other procedure is likely to keep confidential the fact that Assange has been charged,” according to The Washington Post.

The charges would “need to remain sealed until Assange is arrested,” Dwyer wrote.

Federal prosecutors have been investigating Assange over WikiLeaks’ 2010 publication of a trove of US diplomatic cables that proved an acute embarrassment to Washington.

But the charging of Assange in the US could have implications for special counsel Robert Mueller’s probe into whether Donald Trump’s election campaign team colluded with Russia to influence the 2016 presidential vote, and whether Trump tried to obstruct the probe into that.

In July, Mueller charged 12 Russian spies with conspiring to hack Democratic National Committee computers, stealing data from the organisation and publishing those files in an effort to sway the election.

One of the indictments referred to WikiLeaks, described as “Organization 1,” as the platform the Russians used to release the stolen emails.

US media were alerted late Thursday to the inadvertent disclosure, thanks to a tweet from Seamus Hughes, deputy director of the Program on Extremism at George Washington University.

He is known to follow court filings closely.

“The court filing was made in error,” said Joshua Stueve, a spokesman for the US Attorney’s Office in the Eastern District of Virginia, US media reported.

“That was not the intended name for this filing.”

The 47-year-old Assange has been holed up at Ecuador’s embassy in London since 2012, where he took refuge over fears of being extradited to the US over the 2010 WikiLeaks cable dump.

He was originally wanted in London after a British judge ruled he should be extradited to face allegations of sexual assault in Sweden.

The Swedish case has since been dropped, but Britain still wants him to face justice over breaching his bail conditions following his arrest on the sexual assault allegations.

Barry J. Pollack, one of Assange’s attorneys, said, “The only thing more irresponsible than charging a person for publishing truthful information would be to put in a public filing information that clearly was not intended for the public and without any notice to Mr. Assange,” the Post said.

Pollack said he did not know if Assange has been charged.