US federal prosecutors in Virginia have revealed that WikiLeaks founder Julian Assange is facing criminal charges, though the nature of the indictment is still unclear.

The information was disclosed in a filing by federal prosecutors for a case unrelated to Assange, in which Assistant US Attorney Kellen S Dwyer urged a judge to keep the charges sealed.

“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 wrote.

He added that the charges “would need to remain sealed until Assange is arrested in connection with the charges in the criminal complaint and can therefore no longer evade or avoid arrest and extradition in this matter.”

The discovery was first published online Thursday by Seamus Hughes, deputy director of the program on extremism at George Washington University.

The Wall Street Journal reported on Friday that US authorities are confident they will be able to prosecute Assange, which would entail getting Ecuador to revoke his asylum status. Assange has been living in the Ecuadorian Embassy in London since 2012.

Ecuador’s new president has reportedly been critical of the arrangement, saying that Assange is a “stone in our shoe.”

Assange has been under investigation by US authorities for almost a decade in connection with the publishing by WikiLeaks of thousands of confidential US government documents, and more recently because of the group’s involvement in the 2016 presidential campaign.

A spokesman for the US attorney’s office told the WSJ of the revelation that “the court filing was made in error. That was not the intended name for this filing.”