Prosecutors in the United States have charged WikiLeaks founder Julian Assange for publishing classified military and diplomatic documents in 2010, The Washington Post reported on Thursday. The exact nature of the charges is not yet known.

Prosecutors accidentally revealed the sealed indictment in a court filing in an unrelated case in the eastern district of Virginia. Urging a judge to keep the matter sealed, Assistant US Attorney Kellen S Dwyer wrote that “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”. Dwyer later wrote that the charges would “need to remain sealed until Assange is arrested”.

“The court filing was made in error,” said a spokesperson for the US attorney’s office Joshua Stueve. “That was not the intended name for this filing.”

Assange has been living at the Ecuadorian embassy in London for the last five years to avoid extradition to Sweden, where he was facing allegations of rape and sexual assault dating back to 2010. British authorities issued a warrant against him in 2012 for skipping bail to avoid extradition. In May 2017, Swedish authorities dropped the rape charges. Assange fears that the United Kingdom will extradite him to the US regardless.

Barry J Pollack, a lawyer working for the whistleblower, said the revelation was irresponsible. “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,” he said. “Obviously, I have no idea if he has actually been charged or for what but the notion that the federal criminal charges could be brought based on the publication of truthful information is an incredibly dangerous precedent to set.”

On January 11, Ecuador announced that it has granted Assange citizenship. The Ecuadorian foreign ministry said it was concerned about potential threats to the whistleblower’s life from unspecified nations. The United Kingdom Foreign Office has turned down Ecuador’s request to grant Assange diplomatic status.