A federal judge in Virginia declined Wednesday to unseal charges against WikiLeaks founder Julian Assange without official confirmation from the government that the indictment exists.

“Courts cannot perform the delicate balancing required by the First Amendment and common law doctrines under such uncertain circumstances,” Judge Leonie M. Brinkema wrote.

The existence of the case against Assange was mistakenly referenced by a prosecutor filing a motion in an unrelated case and confirmed by The Washington Post and other news outlets. The Reporter’s Committee for Freedom of the Press, a journalism nonprofit, filed a lawsuit to unseal the charges, arguing there is no longer any justification for keeping the details of the case secret.

But Brinkema concluded “an obviously erroneous filing in an unrelated case, public speculation, news stories, and anonymous statements by government officials does not supply a level of certainty comparable to that afforded by official acknowledgment.”

For that reason, she said the claim of a public right to know was “premature,” and a ruling in the group’s favor would allow for “fishing expeditions” based on speculation.

RCFP’s Legal Director, Katie Townsend, said in a statement that the group was “disappointed,” adding, “The disclosure of the nature of the charges against Assange are a matter of public interest and should be made public.”

Federal prosecutors in the Eastern District of Virginia have been investigating WikiLeaks since 2010, when the anti-secrecy site published secret diplomatic cables and military documents. Under President Barack Obama the Justice Department decided charging Wikileaks for those disclosures would run up against freedom of the press. But under Trump, after the website’s 2017 revelation of sensitive CIA cyber-tools, prosecutors took a new look at the case.

The nature of the charges and evidence against Assange remain unclear, sparking concern among free-press advocates.

Assange, who has for over six years lived as a fugitive in London’s Ecuadorian embassy, is also pushing for the indictment to be unsealed.

“Both the public and Mr. Assange have the right to know if charges have been brought against him and the nature of the charges,” Barry J. Pollack, one of Assange’s attorneys, said in a statement Thursday. “The court’s decision allows the government to keep this information secret because the government has refused to confirm that it has charged Mr. Assange, a fact that it previously disclosed in an unrelated case. The government’s intransigence in refusing to confirm what it has previously admitted should be a reason to demand more transparency, not less.”

Wikileaks filed a petition last week with the Inter-American Commission on Human Rights, a regional pro-democracy organization.

In a press release, Wikileaks said that “federal prosecutors have in the last few months formally approached people in the United States, Germany and Iceland and pressed them to testify against Mr. Assange in return for immunity from prosecution.”

Department of Justice officials have declined to comment on those claims.