U.S. federal prosecutors have stepped up efforts to pressure witnesses to testify against WikiLeaks founder Julian Assange, WikiLeaks said on Wednesday, in connection with what it said were secret criminal charges filed by the Trump administration.

WikiLeaks did not mention any names in its public statement. But Assange’s lawyers identified some of those contacted in a document asking the human rights arm of the Organization of American States to demand that the charges be unsealed.

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Reuters obtained excerpts of the document filed with the Inter-American Commission on Human Rights and spoke to one of the persons named.

President Barack Obama’s administration extensively investigated Assange and WikiLeaks after it published hundreds of thousands of secret U.S. diplomatic cables and secret documents detailing U.S.-led military operations in Afghanistan and Iraq.

The administration ultimately decided not to prosecute, however, on the grounds the group’s work was too similar to journalistic activities protected by the U.S. Constitution’s First Amendment.

Late last year, a court filing by prosecutors in an unrelated case referred to a sealed American indictment of Assange. Prosecutors said the filing was made in error and declined to confirm whether any charges had been filed.

Donald Trump praised WikiLeaks during his 2016 presidential campaign for publishing material about Hillary Clinton. Not long after Trump took office, however, then-CIA director Mike Pompeo, now Secretary of State, publicly called it a “non-state hostile intelligence service often abetted by state actors like Russia.”

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Assange, an Australian national, has taken refuge in the Ecuadorean embassy in London since 2012 to avoid extradition to Sweden, where authorities wanted to question him as part of a sexual assault investigation that was eventually dropped.

A spokesman for the federal prosecutors’ office in Alexandria, Virginia, which has taken the lead for several years in investigations into WikiLeaks, did not respond to a request for comment on this story.

According to the document filed to the human rights commission, one of the people contacted by Alexandria prosecutors was Jacob Appelbaum, a Berlin-based U.S. computer expert and hacker.

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Appelbaum told Reuters that while prosecutors offered him broad immunity from prosecution, he had no interest in cooperating or testifying before a grand jury.

Another potential witness targeted by U.S. prosecutors was David House, a Massachusetts computer programmer, the document said. House was involved in setting up a group to support Chelsea Manning, a U.S. soldier who passed on military communications to WikiLeaks and was jailed by U.S. authorities.

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House could not be reached. The American Civil Liberties Union which represented him in connection with the Manning case did not respond to requests for comment.

The Justice Department also contacted American activist and computer scientist, Jason Katz. Katz, who has lived in Iceland since 2011, did not respond to a request for comment sent to that country’s Pirate Party, of which he was a founding member.

Reporting By Mark Hosenball; Editing by Tomasz Janowski and Sonya Hepinstall